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The improvement of the surface properties of AISI 316L type stainless steel by boronizing
Get PDFBorlama, metallerde sert yüzeyler elde etmek amacıyla uygulanan en önemli termokimyasal yüzey işlemlerinden biridir. Borlama işlemi gaz borlama, tuz banyosunda elektrolizle veya elektrolizsiz olarak ve kutu borlamayı içeren farklı şekillerde gerçekleştirilebilir. Borür tabakaları malzeme yüzeyine oldukça yüksek sertlik ve korozyona karşı dayanım sağlar. Bu çalışmada, 850ºC, 950ºC ve 1050ºC sıcaklıklarda 2.4, ve 6 saat sürelerde kalsine borik asit, kalsine boraks ve silisyum karbür içeren tuz banyosunda termokimyasal borlama işlemine tabi tutulan AISI 316L tipi paslanmaz çeliğin yüzey özellikleri incelenmiştir. Borlama işleminden sonra, çelik yüzeyinde oluşan borür fazları ve borür tabakasının basma yönündeki kalıntı gerilme miktarları X – ışınları analizi ile, borlanmış yüzeyin yapısı ışık ve elektron mikroskobu ile, borlanmış yüzeyin pürüzlülüğü pürüzlülük cihazı ile incelenmiştir. Oluşan borür tabaka kalınlıkları artan sıcaklık ve artan süre ile parabolik olarak artmıştır. Borlanmış numunenin yüzeyindeki borür tabakası kompakt ve düz bir tabakaya sahiptir. Borlamada oluşan borür tabakalarında sadece Fe2B fazı oluşmuş, FeB fazı oluşmamıştır. Borlanmış numunede oluşan borür tabakasının oluşum aktivasyon enerjisi 231.886 kJ/mol olarak bulunmuştur. Borür tabakasının basma yönündeki kalıntı gerilme miktarları, borlama sıcaklığının 850°C’den 1050°C’ye yükselmesiyle artmaktadır. Borlama sıcaklığının artmasıyla pürüzlülük değerleri artmaktadır. Ancak, borlama süresinin pürüzlülüğe etkisinde herhangi bir ilişki bulunmamıştır. Anahtar Kelimeler: Borlama, Paslanmaz çelik, borür tabakası, kalıntı gerilme, aktivasyon enerjisi. Austenitic stainless steels represent an important class of materials which possess excellent cryogenic properties and good high-temperature strength. Their mechanical properties are comparable to those of mild steels but offer an excellent general corrosion resistance in the atmosphere, in many aqueous media and oxidizing acids. Particularly, the addition of molybdenum in type 316L provides pitting resistance in phosphoric and acetic acids and chloride solutions, as well as corrosion resistance in sulphurous acid. However, in general, stainless steels are characterized as having relatively poor wear resistance. This fact has led to the development of a number of surface treatments in order to improve their tribological performance without compromising their corrosion resistance, such as nitriding by ion implantation, pulsed plasma nitriding and plasma immersion ion implantation, boronizing. Also, it has been well documented that it is possible to extend the service life of many different parts and components, made of relatively soft substrates, subjected to corrosion and wear, by means of the use of thin hard films such as oxides, nitrides and carbides applied onto their surfaces. However, since such parts could also be subjected to cyclic loading during service, it is of almost importance to evaluate the effect of such hard films on the fatigue properties of the coated substrate, an area which has become an important research topic in the past few years. Mainly, AISI 316 L type steels are used in biomedical applications, automotive industry, ship industry, HVAC (heat ventilation air condition climate) systems and pressure vessel systems. Different superficial hardening processes are commonly applied to metals. Those are generally limited by the metal's original chemical composition as well as the required mechanical properties. Thermochemical methods, for which the superficial composition is locally modified, can produce microstructures and mechanical properties that are completely different from those of the basic metal. atoms and those of the basic metal leads to the formation of new compounds in the superficial layer. Boriding or boronizing is a thermochemical surface hardening technique used for boride-type coating that can be applied to a large range of materials (ferrous metals, non-ferrous metals and cermets). Boriding can be performed in numerous ways, including gas boriding, molten salt boriding, with and without electrolysis, and pack boriding. The produced layers provide an extremely high hardness, good tribological properties and anti-corrosion resistance of the treated surfaces. It is a surface treatment process in which boron atoms are diffused into the material surface between 800 and 1100 ºC. A boride layer with hardness (HV) of 1600?2000 forms by penetrating and diffusing boron to the surface. Boronizing is a prominent choice for a wide range of tribological applications where the control of friction and wear is of primary concern. Boronizing being a thermochemical diffusion treatment can be applied to a wide range of steel alloys including carbon steel, low alloy steel, tool steel and stainless steel. Borides are non-oxide ceramics and could be very brittle. The aim of this study is to clarify the improvement of surface properties of AISI 316 L type stainless steel by thermo-chemical boronizing technique. In this study, boronizing bath was consisting of mixing of the silicon carbide, borax and boric acid in the salt bath. Boronizing process were performed different temperature and time. After the boronizing process, the various tests to determine the properties of boride layer were done. The results of this investigation can be summarized as follows, a) Thickness of boride layer on the surface of boronized AISI 316 L stainless steel increased as a parabolic with increasing temperature and time, b) The boride layers of boronized samples show continuity the surface. The surface structure of boride layer is more homogeneous and more density,c) The basic phase for the boride layer occured with boronizing technique was Fe2B. The FeB did not occur, d)Activation energy of boride layer occurred with boronizing was 231.886 kJ/mol, e)The surface roughness values of boronized samples increased both the increasing additive ratio and increasing boronizing temperature. There is not affair to the effect on the roughness of the boronizing time and the type of the additives, The residual stress of boride layer increased with increasing temperature. Keywords: Boronizing, stainless steel, boride layer, surface roughness, residual stress, activation energy
Investigation of vibrations of circular arches with varying cross-sections
Get PDFEğri eksenli çubuk titreşimlerine ait genel denklemler, altı adet birinci dereceden lineer diferansiyel denklemden oluşmaktadır. Denklemler eksenel uzama, kayma deformasyonu ve dönme eylemsizliği etkilerini içermektedir. Başlangıç değerleri yöntemi kullanılarak, çubuk eksen eğriliğinin ve kesitin eksen boyunca değişimi, mesnetleme şartları ve yükleme durumu belirli olan her çubuğa uygulanabilecek genel bir çözüm elde edilebilmektedir. Elde edilen birinci dereceden değişken katsayılı lineer diferansiyel denklem takımının kesin çözümü, sadece katsayıların sabit olması durumunda mevcuttur. Bu durum, sabit kesitli çember eksenli çubuğu ifade eder. Sabit eğrilik yarıçapı ve sabit kesit alanına sahip çubuk için bilinen kesin çözüm yöntemi, değişken eğrilik yarıçapı ve değişken kesit alanına sahip çubukların düzlem içi titreşim problemlerinin çözümü için de uygulanabilir. Sürekli değişken kesitli, simetrik ve asimetrik geometriye sahip çubuklar, sabit kesit alanına sahip elemanlara ayrılarak çözüm yapılır. Eleman sayısı arttıkça doğru sonuca olan yakınsama da artmaktadır. Böylece eksenel uzama, kayma deformasyonu ve dönme eylemsizliği etkileri ihmal etmeden yaklaşık bir çözüm elde edilmektedir. Bu çözüm, çubuk eksen eğrisi, mesnetleme şartları ve yükleme durumu belli olan herhangi bir çubuğun titreşimlerini incelemede uygulanabilecek genel bir çözümdür. Sürekli değişken kesite sahip çember, parabol ve spiral eksenli çubukların düzlem içi serbest titreşimleri, çember eksenli sabit kesitli çubukların serbest titreşimlerini ifade eden denklemlerin kesin çözümü yardımıyla incelenmektedir. Literatürde verilen örnekler çözülmüş ve elde edilen sonuçlar tablolarla verilerek karşılaştırılmıştır. Elde edilen sonuçların, literatürdekilerle uyumlu olduğu görülmektedir. Anahtar Kelimeler: Eğri eksenli çubuk, sürekli değişken kesit, düzlem içi titreşim.Arch elements are the most simple and the most commonly used structures due to their important applications in many industrial fields. In spite of the fact that considerable amount of attention has been devoted to the analysis of such elements in recent years, there is very limited number of studies available in the literature on the dynamic behavior of arches of continuously varying curvature and cross-sections. Most of works have been done within the scope of Bernoulli-Euler beam theory. This theory is recognized as adequate for common engineering problems. However, Timoshenko beam theory, which takes into account the rotatory inertia and the shear effects, gives a better approximation to the actual beam behavior for the arches having large cross-sectional dimensions in comparison with their span length and for arches in which higher modes of vibration are required. The most important effect on predicting the frequencies of the vibrations of an arch is the axial deformation effect. Only a few works have taken into account the foregoing effects. Almost all of them use the numerical methods and give approximate results. Gutierrez et al. (1989) studied the in-plane vibration of non-circular arches by using polynomial functions and the Ritz method. The classical arch theory was employed. Auciello and Rosa (1994) applied the Euler-Bernoulli beam theory to investigate free dynamics of circular beams. The cross-section variations and different boundary conditions were considered. Liu and Wu (2001) applied the generalized differential quadrature rule based on Kirchhoff assumptions to solve in-plane free vibrations of circular arches with uniform, continuously varying and stepped cross-sections. Karami and Malekzadeh (2004) applied the differential quadrature method to solve free vibrations of circular arches with variable cross-sections by taking into account the effects of axial extension and rotatory inertia. The governing equations of vibrations of arches are six simultaneous linear differential equations of the first order. However, it is more difficult to find general closed form solutions for the dynamic response of arches with arbitrarily varying cross-sections, since the governing equations of such arches possess variable coefficients. When the axial extension, shear deformation and rotatory inertia effects are taken into account, the governing equations of motion become very complicated. Because of this complexity, most of the researchers calculated the natural frequencies of vibrations of arches, based on the classical theory in which the foregoing effects are neglected. The exact solution of the governing differential equations exists only for a circular arch of uniform cross-section. The equations of motion, which take into account axial extension, shear deformation and rotatory inertia effects, have been solved exactly by Tufekci and Arpaci (1998). The same procedure can be used to obtain the solution for the arch with continuously varying curvature and cross-section. The boundary conditions may be arbitrary. In this study, the exact solution for in-plane free vibration of circular arches with continuously varying curvature and cross-section is presented. As an approximation, such an arch is divided into a number of stepped arches with constant curvature and cross-sections. The cross-section of each element is determined by averaging the dimensions of upper and lower bounds. The exact solution of free vibrations for each stepped arch can be obtained by using initial value method. Then overall solution can be expressed in terms of the initial values by satisfying the boundary conditions and the kinetic and kinematic continuity conditions between adjacent arch elements. For a non-trivial solution, the determinant of the matrix of coefficients must be zero. The solutions are also performed for the classical arch theory, which neglects all the aforementioned effects, and for the theory, which takes into account only each effect in order to emphasize their importance. As the number of the stepped arches increase, the fast convergence to the frequencies of the original arch is observed. Five different boundary conditions are also studied for different opening angles. The examples in the literature solved and the results of several methods, such as the finite element, the Rayleigh-Ritz, the cell discretization and differential quadrature methods are compared with the results of this study. Solutions of circular, spiral and parabolic beams are studied in symmetric and asymmetric geometry. The agreement among all these examples is generally good, even if there are some theoretical discrepancies to be pointed out. Keywords: Curved beam, continuously varying cross-section, free in-plane vibration
Modeling and stress analysis of wire ropes with parametric equations
Get PDFTel halat geometrisi imalat tarzından dolayı karmaşık bir yapıdadır. Halatın temel öğelerinden birisi halatın özünü oluşturan Bağımsız Tel Halat Çekirdeği (BTHÇ)’dir. BTHÇ ise ortasında yedi telden oluşan basit düz bir demet ve onu çevreleyen altı adet helisel sarılmış demetten oluşmaktadır. BTHÇ’nin merkez demeti ile dış demetinde yer alan helisel tellerin geometrileri arasında önemli bir fark vardır. Merkez demetin dış telleri tek helisel yapıya sahip iken, dış demeti oluşturan dış teller çift helisel yapıdadır. Bu sebepten ötürü dış demete ait dış çift helisel tellerin modellenmesi özel yöntemlerin kullanılmasını zorunlu kılmaktadır. Bu makalenin amacı, BTHÇ ile tel halatların modellenmesi için yeni bir tekniğin tanıtılması ve bu teknik ile elde edilecek sonuçların literatürde mevcut bulunan sonuçlarla karşılaştırılmasıdır. Öncelikle BTHÇ’nin merkezinde bulunan basit düz tel demetinin modeli oluşturularak modelin doğruluğu kanıtlanmıştır. Ardından BTHÇ’nin dış demetindeki dış tellerin çift helisel geometrisi incelenerek modellenme tekniği üzerinde durulmuştur. Farklı sarım teknikleri ile modellenmesi yapılan BTHÇ’lerin modelleri anlatılmıştır. BTHÇ’nin sonlu elemanlar kullanılarak analizleri sonucunda tel bazında elde edilen sonuçların analitik sonuçlarla mukayesesi yapılmıştır. En son olarak BTHÇ’nin öz olarak kullanıldığı Seale tipi tel halatların modellenmesi ve analizi yapılmıştır. Elde edilen sonuçlar literatürde bulunan analitik ve test sonuçlarıyla karşılaştırılmış ve iyi uyum sağladıkları görülmüştür. Sonuç olarak tanıtılan yeni modelleme tekniği kullanılarak kolay ve daha efektif bir biçimde sayısal analiz yapma olanağı sağlanmıştır. Aynı zamanda uygulanan yöntem daha basit ve daha pratiktir. Anahtar Kelimeler: Tel demet, bağımsız tel halat çekirdeği, çift helisel geometri, Seale tipi halat modelleme.Loads and moments over an helical wire geometry is the fundamental starting point of the wire rope theory. The equilibrium equations are derived from the equilibrium of this wire and it has been presented by Love (1944) in his well-known treatise. Solution of the equilibrium equations under axial loading and pure bending is presented by Love (1944). Frictional and contact effects are not included in the theorethical investigations of the problem due to the complicated geometry. Without taking into account the frictional effects, nonlinear problem of wire rope theory is solved using linearization of the equilibrium equations. A simple wire strand is composed by a straight wire which is wrapped by six outer single helical wires. An independent wire rope core (IWRC) is composed by a simple straight strand as a core strand which is wrapped around by six outer helical strands. The outer wires of the core strand is helical shaped wires while the outer wire of the outer strands is double or nested helical wires. Double or nested helical wire geometry is not included in the analytical solution procedures during the development of the theory of wire ropes. Superposition theory is used for the solutions of the IWRC which takes into account core strand as a straight wire while the outer strands as a single helical wire. IWRCs are widely used as a core for more complicated wire ropes at present. Most of the well known structures are Seale and Warrington IWRC. IWRCs are preferred when the wire rope is run under large lateral compressive loads and additional axial loading capacity is required (Velinsky, 1989). During the literature survey, the first analytical analysis are done by Hruska (1951, 1952, 1953). Hruska did not take into account the frictional effects due to contacts while solving the equilibrium equations given by Love (1944). Only geometrical aspects, axial loading and pure bending are discussed during the early studies. Since then Costello (1990), and later, Utting and Jones (1987) have followed a more fundamental approach. They treat each wire of wire rope as a helically curved rod but make differing assumptions relative to the rope geometry or the interwire contacts. The different theories produce results, which remain close to the experimental values presented by Utting and Jones (1987), but the question of the actual relative displacements and forces within a rope is nevertheless still open. Early studies of the wire ropes under axial loading condition obtained by using finite element analysis are given by Jiang and Henshall (1999). Then this study is extended to three layered strand by Jiang et.al. (1999,2000). These analysis are based on a simple sector of 1/12 or 1/6 of the wire rope cross-section, an arc length or a percentage of the pitch length is taken into account generally. Meanwhile during the literature survey, analytical models conducted for IWRC have not mentioned double helical wire geometry until 2004. Most of the analitical analysis rely on homogenization process except theoretical studies of Elata et.al. (2004), Usabiaga and Pagalday (2008). In this article, wire rope geometry is modelled in a more realistic manner taking into account the double or nested helical geometry of the outer wires of the outer strands for IWRC. To accomplish this, a code is generated named Wire Rope Skeleton (WRS) which creates the centerline of the specified wire in a strand, IWRC or Seale IWRC. Proposed modeling scheme considers each wire with its real solid behaviour. Thus analysis over the wire rope with proposed structure gives more realistic results. To model long wire rope models in 3-D is a cumbersome issue due to the irregularities encountered on the surface of the wires while meshing. The proposed modeling scheme solves the meshing problems of long wire ropes. Also the interactions between wires are defined by contact definitions and friction is taken into account. Realistic material properties are defined and analytical results, test results available in the literature and the finite element analysis results are compared simultaneously. It has been concluded that the proposed modeling procedure works for a wire strand and its development to IWRC and Seale IWRC also gives reasonable results. This analysis technique gives more information about the interwire contacts. As this face this modeling scheme and analysis methodology gives oppurtunity for the future analysis. Keywords: Wire strand, independent wire rope core, double helical geometry, Seale type rope modeling.
Dynamical processes effecting laminar structure in ozone profiles: A case study of Ankara
Get PDFGünümüzde Montreal Protokolü ile kontrol altına alınan klor ve brom içeren ve ozona zarar veren kimyasal bileşikler nedeniyle stratosferik ozon son 30 yıldır azalmaktadır. Stratosferik ozon ve iklim arasında oldukça karmaşık etkileşimler bulunmaktadır. Stratosferik sıcaklık ve taşınımda meydana gelen değişimler stratosferik ozonun dağılımına ve konsantrasyonuna etki etmekte; iklim değişimleri stratosferik sirkülasyonu etkilemekte; stratosferik ozonda meydana gelen değişimler atmosferin radyatif bütçesini ve buna bağlı olarak da iklimini etkilemektedir. Kuzey yarıküre orta enlemlerinde ozon, dinamik etkilere duyarlıdır. Kış sonu ilkbahar başında hem aşağı stratosferden düşey taşınım hem de yatay izentropik taşınım orta enlem aşağı stratosfer bölgelerinde ozon değişkenliği üzerine katkı yapmaktadır. Ozonsonde ile ölçülen ozon verileri ozonun maksimum değeri altında düz bir profile sahip değildir. Özellikle kış mevsimi ya da ilkbaharda elde edilen ozon profillerinde ozon konsantrasyonunun bir sonucu olarak artan ya da azalan ince bir tabaka şeklinde gözlenen bu yapıya lamine ya da filament adı verilir. Lamine yapıyı etkileyen olası termik ve dinamik etkenlerin, seçilen bölge üzerinde etkili olan parametreleri ve bu parametrelerin etki şekillerinin ortaya çıkarılması hedeflenmektedir. Bu çalışmada Ankara’da bulunan ozonsonde istasyonundan alınan 1997-2008 dönemine ait ozon profillerinin lamine yapıları ile troposferik ve stratosferik davranışları araştırılmıştır. Elde edilen sonuçlar bu bölgede hakim olan salınımlar, solar döngü gibi dinamik etkiler yardımıyla incelenmiş; 395, 475 ve 600K seviyeleri izentropik analizleri yapılmıştır. Ozon profillerinin 2005-2008 arasındaki değişimleri ENVISAT’a ait SCIAMACHY uydusundan alınan aynı döneme ait ozon profilleriyle de karşılaştırılmıştır. Sonuçlar lamine yapının özellikle kış ve ilkbahar mevsiminde görüldüğünü ortaya koymakta ve lamine yapıdaki artış toplam ozonda da artışa neden olmaktadır. Anahtar Kelimeler: Ozon, lamine, dinamik süreçler.Stratospheric ozone has been depleted over the last 30 years due to chlorine and bromine containing chemicals that are regulated under the Montreal Protocol nowadays. There is a complex interaction between stratospheric ozone and climate. Changes in stratospheric transport and temperature effect the concentration and distribution of stratospheric ozone; changes in climate effect stratospheric circulation; changes in stratospheric ozone influence radiation budget of the atmosphere and climate. Ozone in the mid-latitudes of Northern Hemisphere is sensitive to dynamical effects. During late winter and early spring both vertical transport and horizontal isentropic transport from the lower stratosphere contribute to ozone variability in the lower stratosphere over mid-latitudes. As well as the information ozone soundings have provided on the vertical distribution of ozone, they are the source of knowledge on ozone amounts. Ozonesondes are the instruments providing year-round profiles of ozone through the lowermost stratosphere of Northern Hemisphere. Measurements of the vertical profile of ozone concentration by balloon-borne ECC (Electrochemical Concentration Cell) ozonesondes have been made since 1994 at least once in a month in Ankara. The ozone profiles measured by ozonesondes do not display a smooth shape below the maximum of the ozone layer. Relatively narrow layers of substantially increased or depressed ozone observed in the measured ozone profiles in the late winter and early spring is called laminae or filament. Laminae basically occur between the tropopause and the ozone maximum and is confined to lower stratosphere. The occurence frequency reveals a very strong seasonal variation with early spring maximum and fall minimum. In recent years the existence of the layers with depleted and enchanced ozone mixing ratios has been reported. The first systematic analysis of the laminated ozone structure was reported by Dobson (1973). In his analysis the criteria for the detection of the laminae in a certain height distance was the change of ozone to be greater than 3 mPa. It has been found that the features of laminae vary with season and latitude. Various further studies with different analysis methods have shown that the laminar structure varies with season, latitude, and the effects of dynamical processes. Laminae in ozonesonde profiles have been used in several studies as an indicator of transport. Following Reid and Vaughan (1991) laminae is defined as a sharp phenomenon deviated from the general shape of an ozone profile by at least 20 nanobars, in order not to confuse with gravity waves. In this study it is aimed to examine the thermal and dynamical effects on the laminar structure and the parameters effecting the study area. Upper level temperatures, pressure heights, potential vorticity, oscillation indices, solar cycle, polar vortex are the most effective of all parameters. Ozone profiles of Ankara-Turkey ozone sounding station for the period 1997-2008 were processed. The data was obtained from WOUDC (World Ozone and Ultraviolet Radiation Data Centre) and TSMS (Turkish State Meteorological Service). Since the data of ozonesondes for the period of 2001-2004 were missing due to software difference problem between WOUDC and TSMS, the laminar structure of the profiles of 1997-2001 and 2004-2008 were examined. The results were compared with the dynamical effects of the region and isentropic analysis were made for the 395 K, 475 K and 600 K isentropic levels respectively. The variation of the profiles for the 2005-2008 period were compared with ENVISAT (Environmental Satellite) SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric ChartograhY) data. Ozonesondes were examined for six pressure levels; ground-630 hPa; 630-400 hPa; 400-250 hPa; 250-158 hPa; 158-100 hPa and 100-30 hPa, and the trend of the ozonsonde for the selected time range was identified. The ground-level trends are found to be larger in general than those in the rest five atmospheric layers. Since laminae is minor compared to the total column ozone, the relation between the indices of the AO (Arctic Oscillation) and NAO (North Atlantic Oscillation) and the total ozone content obtained from TOMS (Total Ozone Mapping Spectrometer)-OMI (Ozone Monitoring Instrument) measurements are examined. The results show that the overall ozone content in laminae has a strong seasonal variation with a maximum in late winter/early spring and a minimum in fall. Laminae seem to contribute to seasonal variation of trends in total ozone. The ozonesonde trend is found to be positive for the selected time range. Keywords: Ozone, laminae, dynamical effects
Eylem çıkarımı ve varlık tanıma için ontoloji tabanlı bilgi çıkarımı ve belge yapı analizinin tümleştirilmesi
Get PDFThis study covers research activity in the field of automatic processing and event extraction from documents in Turkish. Proposed approach benefits valuable hints provided by document structure analysis for extracting information. Approach checks entities and relations of entities across document and verifies them by using relational database integration rules that are defined for each domain event. It contains a morphological analyzer for Turkish, a document structure analyzer and an extraction ontology. Even though there has been an on-going effort for eliminating free-formatted text documents, certain forms of communication continue to be completely unstructured such as fax and e-mail. Proposed approach benefits extraction ontology, where currently available parsing approaches do not use ontology very effectively, mostly depending on rule-based or statistical parsers. Ontology based IE increases portability and scalability of an IE system. Proposed approach requires only extraction concepts when compared to information extraction systems that rely on large set of linguistic patterns. Proposed architecture is tested on a set of 3000 documents in 3 different domains, including data in tabular, list and itemized form. Proposed architecture has an F-Score 99% for extracting information from financial documents, frequent flyer emails and student written letters. Experimental results indicate that it obtained a high performance for detecting document domain, document model, entities and domain events. Main IE tasks can be listed as extracting entities, extracting pre-specified events, extracting relations between entities and events. Experimental results indicate that document structure analysis and ontology based IE techniques mutually benefit each other. In proposed architecture, input document is treated as a combination of document model and event concept, where entities within document are cross-related to each other. Approach determines document model by locating document blocks, and using document models it determines the document domain. Approach also verifies document model by detecting the domain event in the input document. Using document structure analysis approach also determines some of the unknown entity types. Experimental results also indicate that approach successfully locates data in tabular, list and itemized form. For detecting data in tabular or list form it depends on a specific set of titles called "Descriptor Titles" which refer to column or row headers in tables or lists. In Turkish, morphological analysis is more complex when compared to languages like English, because it has agglutinative morphology. Due to the fact that Turkish is a free constituent language, proposed approach focuses on locating domain specific concepts in a sentence using the proposed "Concept Zoning" technique. In case approach detects an unknown triggering verb, using concept similarity calculations, it determines the closest matching event in the extraction ontology. This case is especially useful during system development phase. Benefiting this feature a known domain event with an unknown triggering verb or an unknown domain event made up of known domain concepts can be determined. Approach also detects connected actions. It treats each action as seperate events however, in practice certain events require another event to make sense and its triggering verb contains specific morphological features. Main contributions involved in this thesis are listed as the following items: Test the effect of proposed "Concept Zoning" technique and document layout analysis on entity recognition and event extraction. Develop an ontology editor for designing domain concepts and events for extracting domain specific events in different document domains. Validating extracted information by using both relational database integration and document model validation, and benefit this integration for determining unknown entity types. Keywords: Ontology based information extraction, document structure analysis, entity recognition, natural language understanding.Bu çalışmada, Türkçe belgelerin otomatik olarak işlenmesi ve bu belgelerden bilgi çıkarımı için ontoloji tabanlı bilgi çıkarımı ve belge yapı analizi teknikleri bir arada kullanılmıştır. Geleneksel bilgi çıkarımı sistemleri giriş metnini sıralı kelimeler olarak ele almakta iken, önerilen mimari belge yapı şablonlarının ve belge modellerinin sağladığı bilgilerden faydalanmaktadır. Bu özelliklere ek olarak, belgenin doğruluğunu sınamak için, belgede yer alan varlıklar arasındaki ilişkiler sınanmakta ve çıkarımı yapılmış varlıklar ile gerçek veriler karşılaştırılmaktadır. (Örnek: Müşteri veritabanı). Önerilen yaklaşım, Türkçe için biçimbirimsel analiz modülü, belge yapı analiz modülü ve çıkarım ontolojisi içermektedir. Yüksek miktarda dilbilimsel şablona dayalı çalışan bilgi çıkarım sistemlerinin aksine, çıkarım ontolojisi kullanılarak bilgi çıkarımı için sadece alan kavramı tanımları yeterli olmaktadır. Türkçe’de öğeler cümlenin anlamını bozmadan serbestçe yer değiştirebilmektedir. Bu nedenle kullanılan ontoloji tabanlı ayrıştırıcı ile çıkarımı yapılması istenilen varlıkların cümle içindeki pozisyonundan bağımsız olarak bulunması hedeflenmiştir. Test belgeleri yazılı bankacılık talimatlarını, sık uçanlar e-postlarını ve öğrenci dilekçelerini içermektedir. Bu belgeler serbest metin, tablolu, listeli ve maddesel yapıda veriler içermektedir. Deneysel sonuçlar önerilen mimarinin kısıtlı belge alanları için, belge modeli tanıma, varlıkların ve alan eylemlerinin çıkarımı konularında yüksek başarı elde ettiğini göstermiştir. Anahtar Kelimeler: Ontoloji tabanlı bilgi çıkarımı, belge yapı analizi, varlık tanıma, doğal dil anlama
Doğrudan ayrık tasarım ile Hamiltonian sistemlerde bozucu bastırma
Get PDFIn last decades, there are many ongoing researches on the subject of the modelling and control of complex nonlinear systems. The port-controlled Hamiltonian (PCH) approach is an important modeling and control technique which has been proposed for complex nonlinear systems, especially where electrical and mechanical sub-systems have to be considered together. Besides, the disturbance attenuation problem and the design of controllers under parametric and/or structural uncertainties are important issues in practical applications. In the literature, the H approach has been used to solve the disturbance attenuation problem and to provide robust control for nonlinear systems. While the disturbance attenuation problem characterized by means of the so-called L2 gain of a general non-linear system is required to solve the Hamilton-Jacobi-Isaacs (HJI) partial differential inequality, the same problem for Hamiltonian systems can be reduced to solve an algebraic HJI. For this reason, in literature, some nonlinear H control problems for Hamiltonian systems have been defined and some sufficient conditions have been presented to solve the proposed problems. On the other hand, it is well known that nowadays computer-controlled systems using industrial processors are preferred in engineering practice because of the simplicity and flexibility of their implementation. Therefore, it has been gained more importance to develop modeling and control techniques for discrete-time nonlinear systems. In literature, there are several studies on discrete time nonlinear systems, which can be classified, roughly, in two groups. While one group deals with the concepts of the losslessness, the feedback equivalence and the global stabilization of discrete-time non-linear systems, the other group works deriving the discrete-time counterpart of the H control techniques which are developed using the exact model of the system. It should be noted that a direct discrete-time PBC (Passivity Based Control) control method by using an approximate discrete-time Hamiltonian model has been developed by Astolfi and Laila (2005,2006b), recently. In this study, the discrete-time counterpart of disturbance attenuation problem for a class of Hamiltonian systems (n-dof mechanical systems) is investigated and a sufficient condition for the solution of the problem is given To fulfill, firstly a discrete-time equation, which corresponds to the given Hamiltonian system, is derived by a gradient based discrete-time modeling technique. For this purpose an appropriate discrete gradient definition is presented. Afterwards, using this equation, the disturbance attenuation problem characterized by the means of L2 gain is defined and the results are presented as a theorem, which provides a sufficient condition on the existence of the solution of the proposed problem. In order to obtain the discrete-time version of disturbance attenuation problem for the Hamiltonian systems, a term corresponding to the discrete version of the gradient term in the continuous Hamiltonian model is needed. For separable Hamiltonian systems, the discrete gradient defined in this study satisfies both of the discrete-gradient conditions given in (Gonzales, 1996), but it does not satisfy the first condition precisely, for non-separable case. The main results of this study presented as a theorem is derived under the assumption such that, there exists a discrete gradient which satisfies the discrete-gradient conditions exactly. A detailed discussion is also given for the case where the conditions are not precisely satisfied. The given discussion should be taken into account while the condition HJ1in the theorem is used for the design of discrete-time control rule, especially when slow sampling is used. The proposed direct discrete-time design method is utilized to solve the disturbance attenuation problem of the double pendulum system and tested by simulations. The simulation results have demonstrated that the controller obtained using the method developed in this paper has better performance than the emulator controller for sampled data Hamiltonian systems. It should be noted that the computational complexity of the discrete control rule obtained in this is nearly same as the computational complexity of the emulation controller. This property might provide an important advantage especially in industrial applications. Keywords: Hamiltonian Systems, Discrete-gradient, Discrete-time control, H -optimal control, Disturbance Attenuation.Bozucu bastırma problemi pratik uygulamalar için önemli bir konudur. Literatürde, H∞ yaklaşımı hem doğrusal hem de doğrusal olmayan sistemlerin bozucu bastırma probleminin çözümünde kullanılan tekniklerden biridir. Kapı-kontrollü Hamiltonian (PCH, port-controlled Hamiltonian) yaklaşımı ise mekanik ve elektrik alt sistemlerden oluşan karmaşık doğrusal olmayan sistemlerin modellenmesi ve kontrolü için önerilmiş güçlü bir tekniktir. Ayrıca, teknolojinin gelişim yönüne koşut olarak günümüzde mühendislik uygulamalarında bilgisayarlı kontrol sistemleri tercih edildiğinden, ayrık zamanlı doğrusal olmayan sistemler için modelleme ve kontrol yöntemleri geliştirmek önemli olmuştur. Bu çalışmada n-serbestlik dereceli Hamiltonian sistemler için ayrık zamanlı bozucu bastırma problemi ele alınmış ve bir doğrudan ayrık tasarım yöntemi önerilmiştir. Ele alınan problemin çözümüne ilişkin koşulları verebilmek için öncelikle, verilen Hamiltonian sistemin ayrık zamanlı dinamiklerini gradyan temeli bir ayrık zamanlı modelleme yöntemi ile türetmeye olanak sağlayan uygun bir ayrık-gradyan tanımlanmıştır. Ele alınan sistemler için bozucu bastırma problemi ayrık zamanda ifade edilmiş ve bir doğrusal olmayan durum geribesleme kontrol kuralı ile çözümün varlığına ilişkin yeter koşul bir teorem ile verilmiştir. Genel doğrusal olmayan sistemler için kısmı diferansiyel bir HJI (Hamilton-Jacobi-Isaacs) eşitsizliği olan yeter koşul bu çalışmada bir cebirsel HJI eşitsizliği olarak elde edilmiştir. Önerilen doğrudan ayrık tasarım yöntemi çift sarkaç sisteminin bozucu bastırma probleminin çözümünde kullanılmış ve benzetim yoluyla başarımı sınanmıştır. Benzetim sonuçları, bu çalışmada önerilen doğrudan ayrık tasarım ile elde edilen ayrık zamanlı bozucu bastırma kontrol kuralının emulatör kontrol kuralına göre daha yüksek başarıma sahip olduğunu göstermektedir. Ayrıca, önerilen kontrol kuralının hesap karmaşıklığı, emulatör kontrolün karmaşıklığı ile hemen hemen aynıdır. Anahtar Kelimeler: Hamiltonian sistemler, Ayrık-gradyan, Bozucu bastırma
Osmanlı döneminden günümüze Saraybosna müslüman mezar taşları
Get PDFThis study aims to research the Muslim gravestones during Ottoman period in Bosnia-Herzegovina dating from the period 15th to 19th century by comparing them with the ones in İstanbul, Edirne, Bursa and İznik and to find out the extent of the influence of the earlier periods on today’s gravestone building in the region. The regions of Sarajevo, Mostar, Livno and Glamoç where there are many Ottoman gravestones were specifically chosen in order to carry out the study. In these regions, 277 gravestones were identified and inventoried in terms of their forms, epigraphs and motifs. Each gravestone in the inventory was sketched and the epigraphs on them were deciphered. Besides, taking other studies on the subject into consideration, the gravestones in the region of Bosnia-Herzegovina were analysed. 193 gravestones of them were identified in Sarajevo. This city was a little town until the 15th century but after the Ottoman conquest it became the most important city of the region. First Muslim gravestones’s samples might have been imported to this area from İstanbul or Uskup. Some tombstones does not have epitaphs and they would have been erected during conquest for Ottoman soldiers or Ottoman rulling class who died in Sarajevo. Gravestones which were belonged to 16th century have Arabic epitaphs which begins with “kad entekale el-merhûm…” are very few. Afterwards epitaphs were written in Ottoman Turkish language and frequently those epitaphs began with “Hüve’l-Hayyü’l-Bâkî” or “Ah mine’l-mevt”. However, in 16th century some inscriptions on tombstones are written in Bosnian language by using Bosançitsa alphabeth. Bosnian people after the Ottoman conquest became Moslem but learning Ottoman Turkish language takes long time so they preferred to write inscriptions in Bosnian language. Muslim gravestones in this area are not well-decorated as in capital cities of Ottoman Empire. Women gravestones in this city has only one shape which is called pediment. Very few samples have different form which are in mosque’s hazire or graveyards. Those tombstones belong to upper class families and probably are imported from İstanbul or Üsküp for them. In addition to that some women tombstones have fes but those are very few. Men gravestones have turban. This form is the basic form of Ottoman tombstones. In the center of empire, this basic form was developed by stone-makers. They were educated by masters who are working in palace. They were the members of ehl-i hıref However, in Sarajevo stone-makers had very few models and they were not the member of palace’s artist groups. In Sarajevo center there is a tombstone which has unique form. It is in Ali Pahsa Mosque. M. Mujezinoviç claimed that this grave belongs to son of Tatar Shah. Food stone and head stone are well-decorated, all these symbols can find other tombstones in Sarajevo. These symbols are birds, axe, hand, arrow, bow, yataghan, moon, knobs, animal. On facede of stones there is not any inscription. This grave is dated back to 15th century. Women tombstones have few symbols especially in 19th century, whose facade of stones is decorated by circles, flowers and very few of them have trees (cypres tree). In conclusion, it has been found out that the present-day gravestones of Muslim Bosnians in the region of Bosnia-Herzegovina are built under the influence of both the Ottoman culture and the Bosnian culture of the Middle Ages, and that the gravestones have become a symbol for Muslim Bosnians. However, the present-day gravestones in Turkey differ from the ones in Bosnia-Herzegovina in that they are not built under the influence of the Ottoman culture. This is because Turkey and Bosnia-Herzegovina underwent different developments in the course of their history, especially in the 21st century. Specifically, the Turkish Republic, established after the collapse of the Ottoman Empire, underwent a swift transition period due to fundamental revolutions leading to a different social structure. Keywords: Ottoman gravestones, Bosnia-Herzegovina, Sarajevo muslim gravestones.Bosna-Hersek’in başkenti Saraybosna 15. yüzyıla gelene kadar küçük bir kasabayken Osmanlı döneminden sonra şehir görüntüsü almış ve ardından da bölgenin önemli şehirlerinden birisi olmuştur. Günümüzde hâlâ bölgede Osmanlı döneminden kalan mezar taşları bulunmaktadır. 2007 yılında Saraybosna’da yapılan katalog çalışmasında 15. yüzyıldan 21. yüzyıla kadar tarihlenen 193 mezar taşı tespit edilmiştir. Bölgede kullanılan Osmanlı dönemi mezar taşı modellerinin ilk örnekleri İstanbul ya da Üsküp şehirlerinden 15. yüzyılda gelmiş olmalıdır. İlk gelen mezar taşı modellerinin bazılarının üzerlerinde herhangi bir kitabê bulunmadığı da Kovaçi mezarlığındaki 15. yüzyıla ait olduğu düşünülen kitabêsiz mezar taşlarına bakılarak ileri sürülebilir.16. yüzyıla ait olan ve sayıca çok az bulunan kitabêlerde “kad entekale el-merhûm…” biçiminde başlayan Arapça kalıplar yerini Osmanlı Türkçesi ile yazılmış kitabelere bırakır. Mezar taşlarının üzerindeki kitabêlerde sıklıkla “Hüve’l-Hayyü’l-Bâkî” ve “Ah mine’l-mevt” kalıplarının kullanıldığı anlaşılmaktadır. Bölgedeki Osmanlı dönemi Müslüman mezar taşları hiçbir zaman imparatorluk merkezindeki kadar biçimsel çeşitlilik göstermez, ama biçimleri göz önüne alındığı zaman özgün oldukları söylenebilir. Kadın mezar taşları üçgen alınlıklı, az bezemeli ve gösterişten uzak modellerdir, fakat birkaç istisnai durum da söz konusudur. Erkek mezar taşlarında ise çeşitlilik başlıklardan kaynaklanmaktadır. Çalışmanın sonunda Saraybosna’daki mezar taşlarının hem Osmanlı hem Ortaçağ Bosnasının kültürel etkileri altında yapıldığı ortaya çıkmış ve bu mezar taşları Müslüman Boşnakların sembolü haline gelmiştir. Anahtar Kelimeler: Osmanlı Mezar Taşları, Bosna-Hersek, Saraybosna mezar taşları
Synthesis of miktoarm star polymers via controlled polymerization systems
Get PDFYıldız polimerler birkaç lineer polimer zincirinin bir merkez çekirdeğe bağlı olduğu dallanmış yapılardır. Farklı kollu yıldız polimerler ise sahip oldukları farklı molekül ağırlığı ve kimyasal kompozisyonda kollardan dolayı oldukça ilgi uyandırmaktadır. Kontrollü polimerizasyon sistemleri iyi tanımlanmış kompleks makromoleküler yapıların sentezi için oldukça etkili bir yöntemdir. Bu çalışma, kontrollü polimerizasyon yöntemleri kullanılarak iyi tanımlanmış yapıya sahip farklı kollu yıldız polimerlerin sentezi üzerine yoğunlaşmıştır. Bu amaçla, atom transfer radikal polimerizasyonu (ATRP), kararlı serbest radikal polimerizasyonu (SFRP) ve halka açılma polimerizasyonu (ROP) için uygun fonksiyonel gruba sahip yeni bir başlatıcı, 2-(2-bromo-2-metil-propiyoniloksimetil)-3-hidroksil-2-metil-propiyonikasit 2-fenil-2-(2,2,6,6 tetrametilpiperidinil oksi)-etil ester, sentezlendi. ABC tipli farklı kollu yıldız polimerin eldesi için iki farklı yol izlendi. Birinci yaklaşımda, sentezlenen başlatıcı kalay oktoatın (Sn(Oct)2) katalizör olduğu ε-kaprolaktonun (KL) halka açılma polimerizasyonunda kullanılarak poli(ε-kaprolakton)(PKL) makrobaşlatıcısı elde edildi. Sentezlenen PKL stirenin (St) SFRP’sinde makrobaşlatıcı olarak kullanıldı ve polistiren (PS)-blok-PKL blok kopolimeri sentezlendi. Son olarak, uç grubunda ATRP fonksiyonel grubuna sahip PS-blok-PKL blok kopolimer, tersiyer-butilakrilatın (tBA) ATRP’sinde makrobaşlatıcı olarak kullanıldı ve nihayetinde PKL, PS ve poli(ter-butilakrilat) (PtBA) kollarına sahip, düşük molekül ağırlığı dağılımlı ABC tipli farklı kollu yıldız polimer elde edildi. İkinci yaklaşımda ise, ROP ve SFRP yöntemleri aynı anda kullanılarak tek aşamada PKL-blok-PS blok kopolimeri sentezlendi ve metilmetakrilatın (MMA) ATRP’sinde makrobaşlatıcı olarak kullanıldı sonuç olarak PKL, PS ve poli(metil metakrilat) (PMMA) kollarına sahip ABC tipli farklı kollu yıldız polimer elde edildi. Sentezlenen yıldız polimerler 1H-NMR, GPC ölçümleriyle analiz edildi. Anahtar kelimeler: Farklı kollu yıldız polimer, halka açılma polimerizasyonu, atom transfer radikal polimerizasyonu, kararlı serbest radikal polimerizasyonu.Complex macromolecular structures such as star polymers have been synthesized in the search for polymers with improved mechanical and thermal properties. Star polymers are branched polymers consisting of several linear chains linked to a central core. Among all branched structures, star polymers have been certainly the most investigated architectures, attracting much experimental and theoretical interest. Such species have been very useful in providing further insight into how branching affects the overall properties of polymers in solution or in melt. Some of the applications involving star polymers are the direct result of these structure-property relationships, these polymers being now commonly used as viscosity modifiers in paints and coatings or for their improved processability and mechanical properties compared to their linear analogues. Star polymers containing chemically different arms are termed miktoarm or heteroarm star polymers. Miktoarm is the combination of Greek word miktos meaning "mixed", and "arm". Compared with the corresponding linear block copolymers, miktoarm star polymers exhibit many interesting properties, such as unique phase separation behavior either in bulk or in solution, due to steric hindrance as a result of more than two different types of polymers being brought together at a single junction (core). Although star polymers constitute the simplest branched structure, their synthesis remains challenging, and star polymers are often difficult to synthesize in a well-controlled manner. Due to the complex nature of these macromolecules, living polymerization techniques, such as anionic, cationic have typically been used to obtain well-defined star-shaped macromolecules. The early synthesis of miktoarm star polymers have been based on two general strategies. The first involves living anionic polymers being consecutively reacted with an appropriate multifunctional core (chlorosilane compound) in a consecutive polymer reaction. The second is the reaction of the active chain with divinylbenzene (DVB). Living polymerization is a chain growth polymerization that proceeds in the absence of irreversible chain transfer and chain termination. Living polymerizations provide the maximum degree of control for synthesis of polymers with predictable, well-defined structures. For a long period of time, living ionic polymerization (anionic or cationic) was the dominant living polymerization method. However, in recent years there has been rapid growth in the area of growing controlled/living radical polymerizations (CRP), which have some advantages over anionic polymerization, in that they do not require rigorous experimental conditions. CRP is a simple and robust method for the synthesis of complex macromolecular structures with low polydispersity and well-controlled architecture and functionality. Atom transfer radical polymerization (ATRP) and nitroxide-mediated radical polymerization (NMP) are the most widely used CRP methods. In addition, controlled ring-opening polymerization (ROP) has found wide applications in the polymerization of lactones and lactides. This study focused on the synthesis of well-defined miktoarm star polymers based on combination of controlled radical and nonradical polymerization systems by using a core-first approach employing miktofunctional initiators. An ABC-type miktoarm star polymer was prepared with a core-out method via a combination of ring-opening polymerization (ROP), stable free-radical polymerization (SFRP), and atom transfer radical polymerization (ATRP). First, ROP of -caprolactone was carried out with a miktofunctional initiator, 2-(2-bromo-2-methyl-propionyloxymethyl)- 3-hydroxy-2-methyl-propionic acid 2-phenyl-2-(2,2,6,6-tetramethylpiperidin- 1-yl oxy)-ethyl ester. Second, previously obtained poly(-caprolactone) (PCL) was used as a macroinitiator for SFRP of styrene. As a third step, this PCL polystyrene (PSt) precursor with a bromine functionality in the core was used as a macroinitiator for ATRP of tert-butyl acrylate This produced an ABC-type miktoarm star polymer [PCL-PS-poly(tert-butyl acrylate)] with a controlled molecular weight and a moderate polydispersity. Furthermore, one-pot synthesis of PCL-PS precursor was carried out via combination of ROP-NMP routes. Finally, the subsequent ATRP of methyl methacrylate (MMA) using PCL-PS precursor as macroinitiator gives PCL-PS-PMMA miktoarm star polymer. The obtained polymers were characterized with gel permeation chromatography and 1H NMR. Keywords: Miktoarm star polymer, ring opening polymerization, atom transfer radical polymerization, stable free radical polymerization
Synthesis and characterization of -heterofunctional poly(ethylene oxide) macromonomers
No full textEtilen oksidin (EO) anyonik yaşayan polimerizasyonu makromonomer sentezinde kullanıldı. Bu amaçla, metakriloil ve tienil uç grupları bulunan yeni bir a,w-heterofonksiyonel poli(etilen oksit) (PEO) makromonomeri halka-açılımı polimerizasyonu ile yüksek vakumda sentezlendi. Polimerizasyon potasyum tieniletoksit ile başlatıldı ve 40 0C’ de üç gün devam ettirildi. Yaşayan PEO zincir uçları metakriloil klorür (MAC) ile sonlandırıldı. Ayrıca, iki fonksiyonel gruba sahip olan makromonomerin serbest-radikal polimerizasyonu metakriloil, oksidatif polimerizasyonu ise tienil gruplarından gerçekleştirildi. Metakriloil ve tienil gruplarının varlığı, serbest-radikal ve oksidatif polimerizasyon yöntemleri, 1H-NMR analizi ve GPC ölçümleri yardımıyla aydınlatıldı. Anahtar Kelimeler: Makromonomer, a, w-heterofonksiyonel polimerler, serbest-radikal polimerizasyon, oksidatif polimerizasyon.PEO macromonomers possessing thiophene moiety at one end and methacrylate group at the other end were prepared by a conventional high vacuum line technigue. A general method have been recently developed for synthesis of hetero-functional or hetero-telechelic PEO macromonomers by using a functional alcohol for initiating polymerization of EO followed by terminating with the other functionality. Using the same approach, a novel a,w-heterofunctional poly (ethylene oxide) macromonomer (PEO-makromonomer) possessing methacryloyl and thiophene end groups were prepared by ring-opening polymerization of ethylene oxide initiated by potassium thiophene ethoxide and termination of living ends of PEO with methacryloyl chloride. Polymerization was carried out at 40 0C over 3 nights. The obtained macromonomer has two polymerizable groups: the thiophene ring, with substitution at the 3-position, can be employed in oxidative polymerization while the vinyl group is useful for radical polymerization. The macromonomer, having an electroactive group, was polymerized oxidatively in the presence of FeCl3 as an oxidant. The macromonomer was also used in homopolymerization via vinylic terminus. The reaction involves the free radical polymerization of PEO in the presence AIBN as a thermal initiator. The evidence for successful free radical and oxidative polymerization processes was obtained by GPC measurements Incorparation of methacryloyl and thiophene groups were confirmed by 1H-NMR analysis, free radical and oxidative polymerization processes, respectively. Keywords: Macromonomer, a,w-heterofunctional polymers, free radical polymerization, oxidative polymerization
Synthesis of new porphyrazines and investigation of their properties
Get PDFBu çalışmada, porfirazin sentezinde kullanmak amacıyla beş farklı dinitril türevi elde edilmiştir. Bis(p-nitrobenzil)maleonitril, 6-okso-6,7-dihidro-5H-[1,4]ditiepin-2,3-dikarbonitril ve Bis(2-siyano-etiltiyo) maleonitril optimum şartlarda dahi porfirazin vermemiştir. Ancak 6,7,8,8a-tetrahidro-4aH-[1,4]ditiino-[2,3-b] piran-2,3-dikarbonitril (L1) ve 5-etoksi-5,6-dihidro-[1,4]ditiino-2,3-dikarbonitril (L2) ligandlarının magnezyum butonol içerisinde siklotetramerize olmasıyla hedeflenen magnezyum porfirazinler elde edilmiştir. Sentezlenen bu porfirazinler trifloroasetik asit ile reaksiyona sokularak metalsiz hale dönüştürülmüşlerdir. Çinko ve bakırın asetilasetonat kompleksleri, istenen metalli türevleri vermiştir. Tüm yeni bileşikler 1H NMR, Kütle, IR ve UV-Görünür Bölge spektroskopik yöntemleriyle ve elementel analiz sonuçlarıyla karakterize edilirken, porfirazinlerin elektrokimyasal davranışları CV kullanılarak incelenmiştir. Anahtar Kelimeler: Makrohalka, porfirazin, dönüşümlü voltmetre, elektrokimya.In this study five dinitrile derivatives were synthesized in order to prepare novel porphyrazines. Bis(p-nitro benzylthio) maleonitrile, 6-oxo-6,7-dihydro-5H-[1,4]dithiepine-2,3-dicarbonitrile and bis(2-cyano-ethylthio) maleonitrile did not yield porphyrazines under different conditions. However, magnesium porphyrazines were obtained by the cyclotetramerization of 6,7,8,8a-tetrahydro-4aH-[1,4]dithiino-[2,3-b]pyran-2,3-dicarbonitrile (L1) and 5-ethoxy-5,6-dihydro-[1,4]dithiino-2,3-dicarbonitrile (L2) ligands( which include cis-cyano groups) in the presence of magnesium butanolate. These porphyrazines were treated with trifluoroacetic acid to demetallize. Due to low solubility of metal-free porphyrazine derivatives, metallization process was unsuccessful with copper and zinc acetates. So acetylacetonate complexes of copper and zinc were prepared. Since these complexes were dissolved in organic solvents, they were refluxed with metal-free porphyrazines in THF to yield zinc and copper derivatives. However, elemental analysis results indicated that additional eight Cu(acac)2 units are present in the case of both CuPz1 and CuPz2. All novel compounds were characterized by using 1H NMR, Mass, IR and UV-VIS spectrophotometric methods as well as elementel analysis results. The electrochemical behaviours of all porphyrazines? were investigated by Cylic Voltametry. While electrochemical behaviour of magnesium,metal- free and zinc derivatives were quite similar, those of copper derivatives showed additional features resulting from coordinated copper acetylacetonates. Keywords: Macrocycle, porphyrazine, cyclic voltametry, electrochemistry
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