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Tribological properties of MoN-Ag nanocomposite coatings
Get PDFBirbirleri ile temas halinde olan yüzeylerden, mekanik etkilerle oluşan malzeme kaybı, yüzyıllardır insanoğlunun mekanik problemlerinin başında gelmiştir. Dünyadaki mekanik enerjinin yüzde otuzunun mekanik kayıplara harcandığı düşünülürse, sürtünme ve aşınmanın önemi daha da iyi anlaşılabilir. Teknolojik ilerlemelerle birlikte sürtünme ve bunun neden olduğu aşınma problemlerinin aşılması için sert yüzey kaplamaları kullanılmıştır. TiN, CrN gibi ince film kaplamalar endüstriyel uygulamalar için en yaygın olarak kullanılan kaplamalardır. Molibden esaslı nitrür kaplamalarda, sürtünme ve aşınma açısından oldukça üstün özelliklere sahiptirler. Molibden esaslı kaplamalar da düşük sürtünme katsayısı elde edilmesine rağmen temel problem, karşıt malzemede meydana gelen aşınmadır. Çok sert olan molibden kaplamlara yumuşak Ag, Cu gibi elementlerin ilavesi ile elde edilen yapılar, kuru şartlarda ticari olarak kullanılan kaplamalardan daha üstün sürtünme-aşınma özelliklerine sahiptirler. Bu çalışmada katodik ark ve manyetik alanda sıçratma sistemlerinin hibrit kullanıldığı fiziksel buhar biriktirme yöntemi ile yüksek hız takım çeliği malzemelere üzerine kaplanan farklı Ag içeriğine sahip MoN-Ag kaplamaların Al2O3 karşıt malzeme kullanılarak atmosferik koşullardaki sürtünme ve aşınma özellikleri incelenmiştir. Aşınma deneylerinde katkısız MoN kaplamaların yanı sıra düşük, orta ve yüksek (at.%1.4, %8, %24Ag) Ag içeriğine sahip kaplamalara sürtünme-aşınma deneyi yapılmıştır. MoN yapılara Ag ilavesi ile sürtünme deneyleri sonucunda yüksek Ag içeren kaplamalar dışındaki kaplamalarda önemli bir aşınma görülmemesinin yanında Ag’ün yararlı etkisi özellikle at.%8 oranında Ag içeren kaplamalarda tespit edilmiştir. Anahtar Kelimeler: Nanokompozit kaplama, Mo-N-Ag,hibrit kaplama, mikro-Raman.Nanostructured coatings have been recently of great interest because of the possibility of synthesizing unique physical and chemical properties. Different approaches exist for the production of nanostructured coatings such as superlattice coatings, nano-scale multilayer coating, super lattice coating and nanocomposite coatings. The nanocomposite type coatings have attracted the greatest interest by the researchers. Completely new properties are exhibited by nanocrystalline coatings with decreasing the grain size to about 10 nm. The mechanical properties of these materials are determined by processes in boundary regions because the number of atoms in grain is smaller than in the boundary regions. High fracture toughness can be obtained in the nanocomposite structure due to the nano size grain structure. Currently, two main practices exist for the production of nanocomposite coatings. In the first one, the nanocomposite structure is obtained by the combination of two hard and immiscible phases in one coating (e.g., ncTiN/aSi3N4; a TiSi2 nc TiSi2) while in the other practice, the mixture of one hard (MeN) and one soft (X) immiscible phase (e.g., Zr Cu N, Cr N Cu, Ti Cu N and Mo Cu N) are used. In these coatings, one metal may be converted into nitride as a nanocrystalline phase and the other participated in the growing film without any reaction. Nanocomposite coatings based on hard/hard phases have attracted in recent years and there are now numerous studies that deal with the production, characterization, and application of these coatings. The coatings with hard-soft structure have a very promising structure with respect to tribological applications. One can easily formulate these coatings by selecting the hard and soft phase combinations for the required tribological application. Examples of such formulations have been put forward in our research group especially for coating applications suitable for systems working under boundary lubrication conditions. The main approach used in these formulations relies on functioning of the hard phase (such as MoN) as load bearing material and soft phase (copper, silver, tin, antimony etc.) or their compounds. In this study, further verification of this approach is aimed using a hard-soft nanocomposite system based on Mo-N-Ag. MoN is selected as the hard phase because of its better tribological properties compared to other hard phases. On the other hand silver is an easily shearable soft material that is mainly used in high temperature applications as solid lubricant. Silver also has a potential of forming solid lubricant compounds with the oxides of the hard phase (such as silver molybdates) and it can also react with the formulated oil ingredients and form lubricous structures. For achieving this aim, not only the effect the composition of the coating material but also the effects of different sliding velocity on the tribological behavior is investigated and the results are correlated with the character of the debris that are determined with micro-Raman spectroscopy. Hence, this is a unique study, in which the tribological behavior of the Mo-N-Ag nanocomposite coatings is investigated in detail by taking into consideration both formulation of the coatings and the tribo -mechanical and -chemical properties of the system. Moreover, in this study a hybrid coating system based on cathodic arc and magnetron sputtering that is previously used extensively in our group for the production of other MeN-X type structures, is used for the first time for the production of MoN-Ag nanocomposite coatings. Molybdenum nitride and MoN-Ag nanocomposite coatings were deposited using cathodic arc and cathodic arc + magnetron sputtering hybrid physical vapor deposition techniques. Hardened M2 discs were used as substrates. Hardness of the coatings were measured with a dynamic ultra micro-hardness tester (Fischerscope H 100) equipped with an elongated Vickers type indenter; a total load of 20 mN was applied in 120 steps with a time interval of 0.5s at each step. The phase structure of the coatings was analyzed by a glancing angle X-ray diffractometer. EDS equipped field emission scanning electron microscope (Jeol JSM 700F) was used for investigation of coating growth and wear tracks morphology. Wear tracks and chemical composition of wear debris were examined by 3D profilometer and micro-Raman, respectively. Observations of the wear traces with the micro-Raman investigation showed that formation of lubricious oxide and silver molybdate into the wear track caused decreasing the wear and friction. Silver addition showed its beneficial effect by lowering the wear of counter face material and decreasing the coefficient of friction. Keywords: Nanocomposite coating, MoN-Ag, hibride coating, micro-Raman
Area optimization algorithms in high-speed digital FIR filter synthesis
Get PDFSon on yıl içinde, birden fazla katsayının çarpımı (MCM) problemi, bir başka deyişle, bir değişkenin birden fazla katsayı ile çarpımının en az sayıda toplama/çıkarma işlemleri kullanılarak tasarımı, için etkili algoritmalar önerilmiştir. Bu algoritmalarda, toplama/çıkarma işlemi iki girişli bir işlem olarak kabul edilmekte ve genellikle, hesaplama süresi fazla olan elde ötelemeli toplayıcılar ile gerçeklenmektedir. Bunun yanında, elde korumalı toplayıcılar (CSA) çok girişli toplama işlemlerinin yüksek hızlı tasarımında sıklıkla kullanılmaktadır. Yine de, CSA blok sayısının optimizasyonu için önerilen algoritmalar sezgisellerdir ve minimum sonucu garanti edemezler. Bu makalede, MCM işlemi için gereken minimum sayıdaki CSA bloklarını bulan bir kesin ortak alt ifade eliminasyonu (CSE) algoritması önerilmektedir. Önerilen kesin yöntem gerçek boyutlu örnekler üzerinde uygulanabilse de, MCM probleminin bir NP-bütün problem olmasından dolayı, doğal olarak, kesin algoritmanın ele alamayacağı örnekler mevcuttur. Bu yüzden, bu makalede, büyük boyutlu örnekleri ele alabilen bir yaklaşık CSE yöntemi de önerilmekedir. CSE algoritmaları ile elde edilen sonuçlar katsayıların gerçeklenmesi için kullanılan sayı gösterimlerine bağlı olduğundan bu makalede, ayrıca, katsayıların genel sayı gösterimindeki ifadelerini ele alabilen bir yaklaşık yöntem de sunulmaktadır. Önerilen algoritmalar, rastgele üretilmiş örnekler ve FIR filtreleri üzerinde test edilmiş ve daha önceden önerilmiş CSE ve graf tabanlı sezgisel yöntemler ile karşılaştırılmıştır. Deneysel sonuçlardan kesin CSE algoritmanın sezgisel CSE yönteme göre oldukça iyi sonuçlar elde ettiği ve genel sayı gösterimi altında yaklaşık algoritmanın graf tabanlı sezgisel yöntemle rekabet edebilecek düzeyde ve daha iyi sonuçlar bulduğu gözlenmektedir. Anahtar Kelimeler: Birden fazla katsayının çarpımı problemi, ortak alt ifade eliminasyonu, elde ötelemeli toplama, elde korumalı toplama, 0-1 tamsayı lineer programlama.Digital Finite Impulse Response (FIR) filters are frequently used in Digital Signal Processing (DSP) by virtue of stability and easy implementation. The problem of designing the multiplier block of a digital FIR filter has received a significant amount of attention during the last decade, as the filters require a large number of multiplications, leading to excessive area, delay, and power consumption even if implemented in a full custom integrated circuit. Previous works have focused on the design of filters with minimum area by replacing the multiplication operations with constant coefficients by addition, subtraction, and shifting operations. Since shifts can be implemented with only wires in hardware, the design problem can be defined as the minimization of the number of addition/subtraction operations to implement the coefficient multiplications. This problem is generally known as the MCM problem. In the last decade, many efficient algorithms have been proposed for the MCM problem. These algorithms can be categorized in two classes: Common Subexpression Elimination (CSE) and graph-based algorithms. While the CSE algorithms basically find the common non-zero digit patterns on the representations of the constants, the graph-based algorithms are not restricted to a particular number representation and synthesize the constants iteratively by build-ing a graph.However, in the algorithms proposed for the MCM problem, an addition/subtraction operation is assumed to be a two-input operation that is generally implemented using a Ripple Carry Adder (RCA) block yielding great latency in the implementation of MCM. In high-speed applications, particularly in DSP systems, Carry-Save Adder (CSA) blocks are preferred to RCA blocks taking into account the increase in area.Despite the large number of algorithms designed for the minimization of addition/subtraction operations based on RCAs, there are only a few algorithms proposed for the optimization of the number of CSA blocks. Although these algorithms give good results, they are based on heuristics, i.e., provide no indication on how far from the minimum their solutions are. To the best of our knowledge, there is no exact algorithm proposed for the optimization of the number of CSA blocks in MCM.In this paper, an exact CSE algorithm designed for the minimization of the number of CSA blocks is introduced. In the exact CSE algorithm, initially, all possible implementations of filter coefficients and partial terms using CSAs are found when filter coefficients are defined under a number representation, and a combinational network that represents the implementations of constants is constructed. Then, the minimization of the number of CSA blocks problem is defined as a 0-1 Integer Linear Programming (ILP) problem with a cost function to be minimized and constraints to be satisfied. Finally, a generic 0-1 ILP solver is used to obtain the minimum solution. Due to the NP-completeness of the MCM problem, naturally, there are instances that the exact algorithm cannot handle. Hence, in this paper, we also introduce an approximate CSE algorithm based on the exact CSE algorithm that considers limited implementations of the coefficients reducing the size of the search space to be explored significantly. It is also shown that the approximate CSE algorithm obtains similar results with the exact CSE algorithm. Since the solutions obtained by the proposed CSE algorithms depend on the number representation, in the approximate algorithm, the number of possible implementations of filter coefficients is increased using a general number representation allowing the approximate algorithm to be more effective in area optimization. It is shown that the approximate algorithm under general number representation obtains more promising results than the approximate CSE algorithm. In this paper, the results of the proposed exact and approximate algorithms on a comprehensive set of instances including randomly generated and FIR filter instances are presented. It is shown that the proposed algorithms can be applied on real size instances. Also, the results of the exact and approximate algorithms are compared with those of the previously proposed CSE and graph-based heuristics. As observed from the experimental results, the exact and approximate CSE algorithms find significantly better solutions than the CSE heuristic and the approximate algorithm under general number representation obtains competitive and better results than the graph-based heuristic. Keywords: Multiple constant multiplications, common subexpression elimination, ripple carry adders, carry save adders, 0-1 integer linear programming
High order sliding mode control of a flexible-link robot arm
Get PDFUcunda yük bulunan bir Esnek-Mafsallı Robot Kol (EMRK) hareket kontrolu için Kayma Kipli Kontrol (KKK) ve Yüksek Dereceli Kayma Kipli Kontrol (YDKKK) yöntemleri uygulanmıştır. Esnek kolun istenen bir noktada konumlandırma ve yörünge izleme kontrolu için KKK ve 2nci dereceden YDKKK (2-YDKKK) yöntemleri kullanılarak kontrol algoritmaları türetilmiştir. 1-SD (Serbestlik Dereceli) esnek mafsallı robot kolun hassas hareket kontrolu problemi, özellikle hafif ve esnek yapısı ile matematiksel modelinde yer alan şekil kipleri dikkate alındığında; aşırı doğrusal olmayan ve ayrışmayan dinamik denklemleri ile kontrol alanında oldukça zorlayıcı bir çalışma konusudur. Doğrudan Tahrikli (DT) eklem motoruna sahip EMRK çalışma esnasında oluşan esneme, titreşimler ve farklı kütlelere sahip uç yükü ile birlikte hareket kontrolunun sadece eklem motoruna uygula-nabilen kontrol işareti ile sağlandığı düşünülürse yüksek performanslı kontrolör gerektirdiği açıktır. Dayanıklı kontrol yöntemlerinden, sistem belirsizliklerine karşı etkili ve sistem parametre deği-şimlerinden bağımsız olan KKK yöntemi kullanılmıştır. Yöntemin olumsuzluğu olan çatırtı problemi ise 2-YDKKK yöntemi ile türetilen kontrolör ile giderilmeye çalışılmıştır. Her iki yöntemin deneysel olarak karşılaştırılması ve kontrolörlerin gerçeklenmesi bir Donanımlı Simülatör (Dsim) kullanılarak yapılmıştır. Donanımlı simülatör donanım ve yazılıma sahiptir. Dsim de bulunan donanımlar gerçek sistemin önemli bölümlerini içerir. Bu nedenle doğrudan tahrikli iki motor Dsim de yer almaktadır ve millerinden birbirine akuple bağlanmışlardır. Bu sistemle yapılan deneysel çalışmalara göre 2-YDKKK yönteminin KKK yöntemine göre EMRK hareket kontrolunda daha etkili olduğu gö-rülmüştür. Kontrolörlerin doğrudan tahrikli motor moment salınımlarını bastırmadaki etkinliği harmonik analizi ile karşılaştırılmıştır. Anahtar Kelimeler: Kayma Kipli Kontrol, Yüksek Dereceli Kayma Kipli Kontrol, Esnek-Mafsallı Robot kol, donanımlı simülatör, moment salınım analizi.In this study, Sliding Mode Control (SMC) and High Order Sliding Mode Control (HOSMC) me-thods are applied to a single Flexible Link Robot Arm (FLA) with payload. A sliding mode and high order sliding mode controllers are designed to achieve set point precision positioning control and trajectory tracking control for a FLA. Flexible robot arms have structural flexibilities and resulting high number of passive degrees-of-freedom. They cannot be decoupled due to the highly nonlinear structure. Since the flexible systems have highly nonlinear structure and coupled dynamics, the sliding mode based control approach is chosen a powerful me-thod to overcome the unmodeled and parametric uncertainties. One of the proposed controllers is 2nd order HOSMC method is compared with classical SMC method. Comparison of the methods is experimentally fulfilled using HIL simulator, and additionally torque ripple analysis is made to evaluate of the methods aspect from system harmonics. Direct drive motors are used as actuator in controlled systems. Of all system dynamics affect system harmonics via motor shaft due to the direct drive system that is no gear box. Therefore, harmonics analysis is crucial to in-vestigate of designed controllers effects on system harmonics. To precise set-point and trajectory tracking con-trol of 1-DOF DD FLA has been derived SMC and HOSMC. Sliding Mode Controllers (SMCs) have the robustness properties, while also increasing accuracy by reducing chattering effects. The performance of the designed control methods are tested for the precise position and targeting control of a 1-DOF-DD-FLA system under heavy uncertainties. Comparative results of both methods have been evaluated in real-time using a Hardware-in-the-Loop (HIL) simulator designed for robotics. Especially, HIL simulator for this system includes DD motors and obtained results can be evaluated more realistically according to pure computer simulations. Additionally, torque ripples of whole system with HIL simulator have been determined and their eliminations using for both methods are introduced. HIL simulator is used to implement designed con-troller for a flexible-link arm. Direct drive joint motors are important parts of the direct drive underactuated robot manipulators. Therefore two DD motors take part in HIL simulator and couple through their shaft. One of the motors represents joint actuator, while the other motor is used for generation of the dynamics of the controlled sys-tem via the torque applied to the shaft. The two motors acting as "actuator" and "load torque simulator" are driven separately by a high per-formance controller board. HIL Simulator is ex-pressed briefly as software that is modeled control algorithm and system dynamic model via controller board is integrated with hardware. HIL simulation differs from computer simulation as it involves actual hardware and is not limited with a software-based representation of the system. Main aim is to use HIL Simulator is able to make more realistic analysis about behaviors of the system dynamics in real-time. It is over computer simulation since the simulator incorporates some of the crucial hardware of the actual system that takes part in the loop. For this purpose defined HIL simulation environment is useful to test, analysis and performance evaluation of designed controllers for unde-ractuated robot manipulators. The major contribution of this study is experimen-tal evaluation of 2nd order HOSM controller and SMC for tracking accuracy and robustness against internal and external uncertainties of DD flexible-link arm with the consideration of the full system dynamics effects. The HIL experimental results confirm and depict that the 2-HOSMC me-thod has robust and accurate performance as expected from the HOSM controllers. Additionally, torque ripples of whole system with HIL simulator have been determined and their eliminations using for both methods are introduced. According to the HIL experimental results and torque ripple analysis, using 2-HOSMC has advantages an increased accuracy over the SMC. Keywords: Sliding Mode Control, High Order Sliding Mode Control, Flexible-Link Robot Arm, Hardware in the Loop simulator, torque ripple analysis
The possible effects of temperature conditions on hazelnut farming in Turkey
Get PDFBu çalışmada Türkiye’de gelecek 90 yıl içerisinde sıcaklık koşullarındaki değişikliğin fındık tarımına olası etkileri zamansal ve mekânsal olarak araştırılmıştır. Bu amaçla, ekonomik olarak fındık yetiştiriciliği yapılan Marmara ve Karadeniz Bölgesi çalışma alanı olarak belirlenmiştir. Fındık yetiştiriciliğinde etkili olan en önemli iklim koşullarından biri sıcaklıktır. Fındık yıllık ortalama sıcaklığın 13-16ºC olduğu, 1500 metre yükseltiye kadar olan alanlarda doğal olarak yetişir. Çalışma üç aşamada incelenmiştir. Öncelikle, 1930-2007 dönemini kapsayan geçmiş dönemde ve günümüz koşullarında ekonomik olarak fındık yetiştiriciliği yapılan alanların fındığın doğal ortam koşullarına uygunluğu sorgulanmıştır. İkinci aşama olarak, sıcaklık koşullarıyla fındık verimliliği arasındaki ilişki istatistiksel olarak belirlenmiştir. Üçüncü aşama olarak, bölgesel iklim modelinden (RegCM3) A2 senaryosuna göre elde edilen sıcaklık koşullarının gelecek 90 yıl içindeki değişimi (2011-2020…2091-2100), her 10 yılın ortalaması alınarak Matlab programında analiz edilmiş, gelecek her on yılda fındık yetiştiriciliğine uygun olan alanlar belirlenmiştir. Sonuç olarak, çalışma alanındaki sıcaklık koşullarının fındığın sıcaklık isteği ile uygunluk gösterdiği tespit edilmiştir. Sıcaklık koşullarıyla fındık verimi arasında p<0.01 anlam seviyesinde %50’nin üzerinde istatistiksel bir ilişki saptanmıştır. Bölgede önümüzdeki 90 yıllık süreçte sıcaklıkta 6ºC’ye varan bir artış belirlenmiştir. Bu durumun fındık alanlarında yatay ve dikey yönde değişime neden olabileceği tespit edilmiştir. Buna göre, 0-250 metre arasında yer alan sahil kuşağında fındık yetiştiriciliğini olumsuz etkilenebileceği, dikim yapılan alanların dikey yönde değişim göstererek bugün için fındık tarımına uygun olmayan 1500 metrenin üzerindeki alanların tarıma elverişli sahalar haline geleceği öngörülmektir. Anahtar Kelimeler: Sıcaklık koşulları, fındık tarımı, Türkiye.Climate, one of the main important elements of the natural environment, has a determining role in natural and human life. According to the recent climate change impact assessment studies framework; agriculture, vegetation, water resources and tourism are the sectors affected directly by temperature changes. Temperature, being one of the most important climatic parameters, has a direct impact on the hazelnut farming. In this study, the possible effects of temperature conditions on hazelnut farming in Turkey within the next 90 years were examined. For this purpose, Kocaeli, Sakarya, Düzce, Samsun, Ordu, Giresun and Trabzon provinces, which are the most favorable habitat for hazelnut cultivation in Marmara and Black Sea Region, were selected as study area. Hazelnut is a quite selective plant considering its climatic requirements. Unlike other types of fruits in temperate climate, it flowers during winter months. This is the most significant factor limiting the cultivation of hazelnut in many regions. It can be naturally cultivated under humid temperate climatic conditions. Regions with annual mean temperature of 13 - 16 °C and at a height below 1500 meters have the most favorable conditions for cultivation. The data on production of hazelnut (ton) and area (hectare) was taken as raw data from 15 - year period from 1993, when it started to be recorded reliably, to 2007. It was converted into a usable form through Matlab 7.0 program. The yield data which used for relationship between climate and yield were computed by dividing total yearly production. Meteorological station data of annual mean temperature which covering 1930-2007 period were examined to determine the present day temperature conditions. In order to identify future temperature conditions, temperature data set which obtained from regional climate modeling (RegCM3) according to the A2 scenario for future 90 years (2011-2020, 2021-2030,...2091-2100) was investigated. Re-analysis data covering 1960-1990 were used for reference period calculations. Since the goal here was to conclude an overview about the production quantity and farming area, hazelnut yield data (ton / hectare) obtained from hazelnut production (ton) and area (hec-tare), were used as agricultural data. At the first stage of the research, annual mean temperature data set covering 1930-2007 time period was analyzed from the view of conformity with the hazelnut's requiring temperature and altitude conditions for a favorable cultivation in the research area. Firstly, temperature data were corrected according to standard atmosphere lapserate (0.649/100 m). Then hazelnut farming areas were determined according to the hazelnut temperature conditions, between 13 - 16 ºC annual mean temperature limits. In the same manner, the areas below the limit altitude value 1500 meters height were determined. After these two defined areas according to hazelnut's temperature and altitude requests are combined together to estimate the layout of possible hazelnut cultivation area. At the second stage of the research, detailed statistical analyses were performed to investigate the relationship between temperature conditions and hazelnut yield data. In order to examine this relationship Pearson correlation coefficient analysis was applied to temperature conditions and hazelnut yield. According to this analysis, the relationship between annual mean temperature and hazelnut yield was determined to be at the statistically meaning level of p < 0.01 and over 50 %. As a result, it is clearly seen that annual average temperatures are highly effective on yield of hazelnut. For determining the effects of future temperature conditions on hazelnut farming, temperature data set which obtained from regional climate modelling (RegCM3) with A2 scenario for next 90 years was used. The data were handled with the flexible Matlab program code builded during the research. To do this analysis, average ten years were simulated by the Matlab program code and comprehensive graphical analyses were represented. A temperature increase up to 6ºC in the region over the next 90 years was identified depending on the future climate scenarios. Therefore, it is concluded that the temperature change may cause horizantal and vertical movements of hazelnut farming areas. Taking this conclusion into account, it is predicted that hazelnut cultivation in the coastal zone of 0-250 meters height can be negatively affected and areas over 1500 meters height which are not suitable for farming today can become favorable for hazelnut planting due to vertical area changes. Keywords: Temperature conditions, hazelnut farming, Turkey
Investigation of changes in metabolites during tomato paste processing
Get PDFPek çok endüstriyel ürünüyle domates, oldukça önemli ve bol tüketilen meyvelerin başında gelmektedir. Domatesin zengin besin değeri, gıda işlemenin antioksidan aktiviteye sahip değerli bileşenlerine etkilerinin araştırılmasını önemli hale getirmiştir. Genel olarak salça üretimi; yıkama, parçalama, ayıklama, pulper ve ince elekten geçirme, buharlaştırma, kutulama, pastörizasyon (veya sterilizasyon ve aseptik ambalajlama) ve soğutma aşamalarından oluşmaktadır. Bu çalışmada üretim sürecinin her bir aşaması LC-QTOF-MS yöntemiyle tüm metabolitleri açısından analizlenerek meydana gelen değişimler incelenmiştir. Tüm metabolitler değerlendirildiğinde, toplam 3177 metabolitle ilişkili kütle sinyalinin %40’ından fazlasının işleme esnasında önemli ölçüde değiştiği tespit edilmiştir. Metabolik profilde önemli ölçüde farklılığa neden olan iki üretim basamağı ise parçalama ve kabuk ve çekirdeğin ayrılması olarak bulunmuştur. Örnekler arasında yapılan karşılaştırmalar, meyvede salçaya göre önemli ölçüde yüksek bulunan bileşikler arasında bir grup glikozilatlanmış alkoloidler, hidroksisinamat, flavonoidler ve tomatozit A’nın bulunduğunu göstermiştir. Diğer taraftan sadece likoperozit H ve naringenin meyveye oranla salçada yüksek bulunmuştur. Salçada düşük düzeyde bulunan bileşikler, kabuk ve çekirdeğin uzaklaştırılması sırasında üretim zincirinden kaybolmuştur. Bu nedenle, kabuk ve çekirdek fraksiyonu çok sayıda flavonoidin yanı sıra, çeşitli alkoloidleri de içermektedir. Meyve ve parçalanmış meyve arasında önemli ölçüde farklı olan bileşikler incelendiğinde ise çeşitli flavonoidlerin ve glikoalkoloidlerin olduğu belirlenmiştir. Özellikle narincenin, narincenin kalkon, rutin, rutin apiozit, kamferol rutinozit ve likoperozit H bileşiklerinin parçalama işleminden sonra 1.3-4.3 kat oranında arttığı tespit edilmiştir. Anahtar Kelimeler: Domates işleme, salça, metabolit, flavonoid, glikoalkoloit, LC-QTOF-MS.Tomato is an important and highly-consumed fruit that has many different industrial products. The consumption of tomatoes has been proposed to reduce the risk of several chronic diseases such as cardiovascular diseases and certain types of cancer. In addition, tomato consumption leads to decreased serum lipid levels and low density lipoprotein oxidation. The nutritional value of tomato created a great interest in the effect of processing on its valuable compounds showing antioxidant activity. In general, tomato paste production includes the basic steps of cleaning, breaking, finisher-separating the pulp from skin, and seeds, evaporating, canning, pasteurizing (or sterilizing and aseptic packaging), and final cooling. In this study, every step of processing was investigated in detail to elucidate the changes in untargeted metabolomics. In order to determine which of the processing steps mostly affects the overall metabolite composition of the final paste, all tomato samples were extracted in aqueous-methanol and analyzed using an untargeted LC-QTOF MS - based metabolomics approach. The mass profiles obtained were processed and aligned across all samples using MetalignTM software. After filtering out mass signals that were < 10 times the local noise in all 30 samples, the resulting data matrix contained intensity values (calculated as peak heights) of 3177 mass signals aligned across all samples. The mass intensity data were 2 log-transformed and then subjected to multivariate analysis using GeneMathsTM software. The results of LC-QTOF MS-based metabolomics approach was applied on a principal component analysis (PCA) diagram. The first principal component (36% of the total variation in the dataset) pointed to the most dominant step in the paste-production process, and it clearly corresponded to the separation of seed and skin from the rest of the tomato material. The second component explained 20% of the variation and corresponded to the step-wise processing from fruit to paste. The largest overall variation between the 5 biological replicates at each processing step, calculated over all 3177 mass signals detected, was observed within the pulp samples where this value was 32% in all the other samples. The most important differences in those metabolites were observed in between fruit and paste, fruit and seed and the skin, and fruit and breaker. In general, nearly 43% (1356 signals) of the total number of mass signals differed significantly (p 0.05) between fruit and paste samples. Likewise, about 60% of the signals were statistically different between fruit and seed and skin, and about 25% between fruit and breaker. Among the compounds that were significantly higher in fruit versus paste were a range of glycosylated alkaloids (lycoperoside- and esculeoside-isomers), hydroxycinnamates (mono-, di- and tricaffeoyl derivatives), flavonoids (specifically naringenin chalcone and two of its glycosides), and the saponin tomatoside A. The ratio for the compounds higher in the fruit compared to the paste, changed from 1.4 to 62.3 as in pantothenic acid-hexose and tomatoside A, respectively. In contrast, only the alkaloid lycoperoside H and the flavonoid naringenin were, respectively, 2-fold and 6-fold higher in paste compared to original fruit. Clearly, most compounds that were lower in paste were lost from the production chain upon removal of the seed and skin fraction. This fraction, therefore, contained relatively high levels of all flavonoids, as well as several alkaloids. On the other hand, compounds that were relatively low in the seed and skin fraction were several hydroxycinnamates (chlorogenic acid and 3 caffeic acid hexosides), citric acid, a glycoside of pantothenic acid (vitamin B5), and UDP-Glucose which is 22-fold higher than in the seed and skin fraction. For the rest of the compounds the seed and skin fraction contained 3 to 14-fold higher amounts compared to the fruit as in coumaric acid-hexose, and -tomatin, respectively. When the compounds that were significantly different between fruit and breaker samples were investigated, again several flavonoids and glycoalkaloids were determined. The relative levels of compounds including, naringenin, naringenin chalcone, rutin, rutin apioside, kaempferol-rutinoside, lycoperoside H, increased with ratios of 1.3 to 4.3-fold after the breaking treatment as compared to the intact fruits. On the other hand, only pantothenic acid-hexose, UDP-Glucose, ferulic acid-hexose decreased by 25% to 50% when fruit was processed into breaker. Keywords: Tomato processing, paste, metabolite, flavonoid, glycoalkoloid, LC-QTOF-MS.
A fuzzy multiple attribute decision making approach for spread mooring system selection
Get PDFÇok noktalı tanker-şamandıra bağlama sistemi (spread mooring system), belirli coğrafik konumlarda, pek çok olası hava koşulu altında tankerlerin sabit bir konumda bağlanmasında kullanılan bir açık deniz yapısıdır. Bu sistemler, çeşitli su derinliklerinde kurulabilmeleri, değişik tonajdaki gemilerin bağlanmasına olanak sağlamaları ve uzun servis yaşamları nedeniyle oldukça yaygın bir şekilde kullanılan bağlama şeklidirler. Çok noktalı tanker-şamandıra bağlama sistemini tasarlarken, ilk yatırım maliyeti, işletme maliyeti, güvenilirlik, şamandıra bağlama donanımı özellikleri, işlem zamanı, bağlama yükü büyüklükleri vb. gibi sistem tasarımı üzerinde etkili olan pek çok öz niteliği dikkate almak gerekmektedir. İlk yatırım maliyeti gibi bazı öz nitelikler deterministik özellikler içerirken, güvenilirlik gibi bazı öz nitelikler ise bulanık özellikler içermektedirler. Bu nedenle, farklı coğrafik bölgelerde kullanılacak en uygun bağlama sisteminin seçim süreçlerinde, bu kararlara rehberlik edecek bir bulanık algoritmaya gereksinim vardır. Pek çok belirsizliğe sahip tanker-şamandıra bağlama sistemi konfigürasyonları arasında, en uygun bağlama sistemine karar vermek için, Bulanık Çok Ölçütlü Karar Verme yöntemlerinin kullanımı problemin bulanık doğası nedeniyle, uygun bir yaklaşım olacaktır. Bu çalışmanın amacı, çok noktalı tanker-şamandıra bağlama sistemleri için en uygun bağlama şekline karar verebilecek bir yöntem geliştirmektir. Önerilen yöntem, bulanık ortamda çok noktalı bağlama sistemi seçim işleminde, problemin çözümlemesi ve öz niteliklerin ağırlıklarının belirlenmesi aşamasında bulanık AHP (Analitik Hiyerarşi Süreci), bağlama sistemlerinin sıralanması ve seçimi aşamasında ise bulanık TOPSIS (İdeal Çözüm Benzerliği Tercih Sıralaması Tekniği) yöntemlerinden oluşur. Geliştirilen yöntem, endüstride pek çok karar verme probleminde rahatlıkla kullanılabilecek esnek bir yapıya sahiptir. Anahtar Kelimeler: Çok noktalı bağlama sistemi, karar verme, bulanık çok öz nitelikli karar verme yöntemleri, tanker.Decision-making is a procedure to find the best one among a set of feasible alternatives. All decision-making processes are basically fundamental activities of human being. They also become difficult processes in consequence of having multiple and conflicting criteria in vagueness and fuzziness. Decision-making procedures are usually called Multiple Criteria Decision Making (MCDM) and mostly involve Decision Makers subjective judgments and preferences. Multiple Criteria Decision Making is classified into two categories depending on whether the problem is a selection problem or a design problem, namely, the Multiple Attribute Decision Making (MADM) and the Multiple Objective Decision Making (MODM) (Lai and Hwang, 1994). Multiple Attribute Decision Making methods evaluate and select the desired one from a finite number of alternatives, which are characterized by multiple attributes. Multiple Objective Decision Making consists of a set of conflicting goals that can not be achieved simultaneously. Usually Multiple Objective Decision Making concentrates on continuous decision spaces, has several objective functions and can be solved with mathematical programming techniques. The present Multiple Attribute Decision Making methods become defective when rates of a decision matrix used to solve of a problem are foggy. Whereas, most of the real life problems involve vagueness and fuzziness, and decision makers have difficulty to choose among the many alternatives and to specify the best alternative. Consequently, Fuzzy Multiple Attribute Decision Making (FMADM) techniques and methods have to be used to overcome the aforementioned difficulties. Fuzzy Multiple Attribute Decision Making presents its most powerful aspect by actualizing the complex systems which have uncertainty in their definitions. Fuzzy Multiple Attribute Decision Making has an advantage compared to the other techniques for the solution of systems which are most complex, ambiguous and uncured with traditional methods. The spread mooring system (or multiple point mooring system) is an offshore mooring system that allows a tanker to moor at a fixed geographic location at many possible weather conditions. These systems can be utilised extensively for the applications that depths. There are several criteria affecting the design of a multiple point tanker-buoy mooring system such as investment cost, operational cost, reliability, operation time, Some of these criteria like investment cost depends on deterministic factors while the others such as reliability has fuzzy parameters. Therefore, there is a requirement of a fuzzy algorithm that guides decisions to the most proper type of mooring system for different regions. The approach of using Fuzzy Multiple Attribute Decision Making will become the most proper method for tanker-buoy system configuration selection that has much uncertainty. The objective of this research is to improve a methodology for selecting the most appropriate multiple point mooring system configuration for the gas companies situated near Yarimca on the Eastern Marmara Sea Region in Turkey. For this purpose, Fuzzy Multiple Attribute Decision Making methods based on Fuzzy Set Theory are employed to select the best one of 12 different tanker-buoy mooring alternatives. Fuzzy Set Theory, which was first introduced by Zadeh (1965) to deal with the kind of qualitative, imprecise information or ill-structured decision problems, has been applied for modeling tool for complex systems in the recent years. Fuzzy expressions are more natural for humans than rigid mathematical rules and equations. In this study, proposed methodology is based on fuzzy AHP (Analytic Hierarchy Method) method in analyzing the structure of the mooring system selection problem and determining of the weights of the attributes, and fuzzy TOPSIS (Technique for Order Performance by Similarity to Ideal Solution) method for ranking the mooring systems in fuzzy environment. In the conclusion part of the study, the results of the fuzzy selection process is evaluated. The proposed hybrid Fuzzy Multiple Attribute Decision Making methodology results indicate that A10 (2 anchors and 3 aft buoy mooring) is the best alternative, so this alternative system has to be selected. These results show that the best multiple point tanker-buoy mooring system selection problem can be handled in a more flexible, robust and realistic way through the proposed solution methodology. Also, this methodology used for decision making problems has very versatile and flexible structure. Therefore, it can easily be used and applied with slight modifications in other marine technology related selection problems. Keywords: Spread mooring system, decision making, fuzzy multiple attribute decision making methods, tanker
Risk-based analytical modelling of managerial processes in shipping business
Get PDFGemi işletmeciliği faaliyetleri uluslararası platformda, yüksek rekabet koşulları altında ve her geçen gün yükselen öz-denetim olgusu gibi kısıtlar altında yürütülmektedir. Bu tür kısıtlar, gemi işletmeciliğinde profesyonel anlayışa geçişe ve yenilikçi yürütme faaliyetlerine sürekli gelişim hedefi ile yönelimi tetikler. Son yıllarda, sertifikalandırma kuruluşları ve denizcilik danışmanlık grupları gemi işletmeciliği idarecilerine Entegre Yönetim Sistemini (EYS) ileri bir çözüm aracı olarak önermektedir. Gemi işletmeciliğinde EYS uygulamalarının kapsamı uluslararası tanınmış standartların gemi güvenliği ve gemilerden kaynaklanan kirliliğin önlenmesi ile ilgili zorunlu denizcilik kurallarıyla birleştirilmesi esası üzerinedir. Bu noktada, standart gereksinimlerinin uyumluluğu ve ilgili kuralların gemi işletmeciliği yönetim organizasyonuna entegrasyonu iki temel sorun olarak ortaya çıkmaktadır. Bu araştırma ile Bulanık Bilgi Aksiyomu (BBA), Hata Ağacı Analizi (HAA), Analitik Ağ Süreci (AAS) ve diğer başlıca Çok Ölçütlü Karar Verme (ÇÖKV) yöntemlerini de içeren bir Risk Bütünleşik Karar Destek Sistemi (RBKDS) geliştirildi. RBKDS, Veri Tabanlı Yönetim Sistemi (VTYS), Model Esaslı Yönetim Sistemi (MEYS), BBA esaslı Model Seçim Arayüzü (BBA-MSA), Entegre Süreç Yönetim Modülü (ESYM), İdari Karar Verme Modülü (IKVM) ve Risk Kontrol Ve Yönetim Modülü (RKYM) gibi unsurların bütünleştirilmesi ile oluşmuştur. Tamamlanan prototip uygulama ile RBKDS’ın EYS’nin süreç temelli entegrasyonu ve gemi işletmeciliğinde yönetimsel süreçlerin risk temelli analitik çözümü konusunda gemi işletmeciliği idarecilerini destekleyen nitel çıktılar ortaya koyduğu görülmüştür. Süreç idaresi prosedürlerinin yeniden tasarımına karar desteğinin yanı sıra, RBKDS, ayrıca farklı standartlar arası uyumsuzluk risklerini de göz önünde bulundurarak yönetimsel süreçler üzerine etkin karar vermeyi sağlamaktadır. Anahtar Kelimeler: Gemi işletmeciliği, karar destek sistemi, entegre yönetim sistemi.Relevance to legislation in shipping business cycle, the International Maritime Organization (IMO) principally governs the safety and environmental protection via Flag State Implementation (FSI) and regional Port State Control (PSC) authorities in accordance with the designated Memorandum Of Understandings (MOUs). Although the IMO has adopted various conventions, mainly concerning marine safety, security, pollution prevention, and other relevant issues, enforcement of the international commitments and standards in trading activities of ships necessitate the involvement of maritime stakeholders. The IMO declared that there are now enough regulations in place and the problem is one of implementation and enforcement. In accordance with the recent trends in international maritime legislation, the implementation process of regulatory regime has become a competitive factor for the market players to achieve the sustainable development target in maritime transportation industry. Industrial response to this trend recalls the self-regulation. It is appeared as relatively a new regime for shipping business initiatives in maritime transportation industry. Extensively, the self-regulation dominates the industry and it mainly enforces the maritime stakeholders involvement in enhancement of the safety/environmental aspects for shipping business. Beside safety and environmental contributions, the self-regulation spontaneously ensures legislative performance of the relevant organizations such as classification societies, insurers, cargo owners, shippers, shipbrokers, ship managers, terminal operators and, ship financiers in trading activities satisfactorily. Implementation of an Integrated Management System (IMS) is one of the most effective and concrete instruments of managing the self-regulation phenomenon in order to respond to increasing demands from maritime society. In principle, the concept of IMS practices in shipping business is based on combining internationally recognized voluntary standards with the mandatory maritime 8regulations that are mainly concern with ship safety and the prevention of pollution from ships. In the early design phase of an IMS, cooperative efforts of maritime consultancies and relevant shipping executives targets to enable maximum improvement in managerial processes while reducing the costs and excessive bureaucracy in implementation of redesigned procedures. As potential clients, the third party groups such as cargo owners and contracted charterers have closely monitored the performance effects of IMS integration into professional shipping companies. Therefore, the managerial efforts are extremely valuable for the purpose of benefit from IMS implementations, which increase the reputation of ship management companies and provide an enormous trading advantage in maritime transportation industry. This research develops a Risk Integrated Decision Support System (RIDSS) based on a multi-methodological background includes Fuzzy Axiomatic Design (FAD) and Fault Tree Analysis (FTA), as well as Analytic Network Process (ANP) and other principal MCDM methods. The initial focus of the RIDSS is to reveal quantitative outcomes in order to encourage relevant shipping executives towards process-based integration of an IMS also to enhance risk-based analytical modelling of managerial processes in shipping business. The RIDSS consists of various modules such as Database Management System (DBMS), Model Base Management System (MBMS), FAD-based Model Selection Interface (FAD-MSI), Integrated Process Management Module (IPMM), Executive Decision-Making Module (EDMM), and Risk Control And Management Module (RCMM) with a high level of integrity. To demonstrate the proposed RIDSS, the mostly encountered managerial processes in commercial, technical, and operational levels of shipping business are then addressed and modelled. Specifically, the prototype application of the RIDSS incorporates the following process:(i) shipboard personnel recruitment, (ii) familiarization and training, (iii) performance appraisals of marine suppliers, (iv) marine equipment/spare purchasing, (v) fleet maintenance planning, (vi) accident analysis and prevention, (vii) Ship docking operations management, (viii) performance measurement for emergency drills. Besides decision aid to redesigning of process execution procedures through IMS requirements, the RIDSS also enables an effective decision-making on managerial processes even considering the potential risks of regulatory incompliance. Keywords: Shipping business, decision support system, integrated management system.
Strategic management modelling for chemical tanker management
Get PDFKimyasal tankerlerde taşınan yüklerin çok farklı teknik özellikleri vardır ve bu yüklerin birçoğu insan hayatı ve çevre için tehlikeler içermektedir. Bu gemilerdeki küçük bir hata bile, büyük felaketlerle sonuçlanabilir. Türk kimyasal tanker filosu, geçtiğimiz üç yıl içinde iki kat büyümüştür. Bu büyüme, beraberinde bazı riskleri de ortaya çıkarmıştır. Bu yüzden, Türk kimyasal tanker işletmelerinin stratejik yönetim ilkeleriyle yönetilmeleri gerekmektedir. SWOT analizi yöntemi, strateji üretmenin ilk adımı olan bulunulan konumun tespitinde kullanılan yöntemlerden en etkili yollarından biridir. Bundan dolayı, mevcut durum tespitinde güçlü yanlar, zayıf yanlar, fırsatlar ve tehditler (SWOT) analizi yöntemi ve bu yöntemle elde edilen faktörlerin ağırlıklandırılmasında analitik hiyerarşi süreci (AHP) kullanılmıştır. Bu makalede, dünya ve Türk kimyasal tanker işletmeciliği detaylı olarak incelenmiş; kimyasal tanker işletmeciliğini etkileyen pozitif ve negatif faktörler SWOT analizi yöntemiyle tespit edilmiş ve bu faktörler AHP yöntemiyle ağırlıklandırılmıştır. Daha sonra, zayıf yanları güçlü yanlara, tehditleri ise fırsatlara çevirecek model stratejiler üretilmiştir. Bu modeller, kimyasal tanker işletmeciliği için yönetim ve organizasyon yapısı oluşturulması; karar verme yöntemlerinin gemi işletmeciliğinde kullanılması ve örnek uygulama; tehlike analizi yöntemlerinin kimyasal tanker işletmeciliğinde kullanılması ve örnek kaza değerlendirmeleri; personel değerlendirme ve eğitimi için tasarlanan ve gemiadamlarının performanslarının sayısal olarak değerlendirilerek sonuca göre uygun eğitim programı öneren DEPEDES yazılımıdır. Bu çalışmanın amacı, Türk kimyasal tanker işletmeleri için stratejik yönetim modeli oluşturarak, Türk kimyasal tanker işletme endüstrisini daha emniyetli, daha çevreci ve daha karlı hale getirmektir. Anahtar Kelimeler: Gemi işletmeciliği, stratejik yönetim, SWOT-AHP.Worldwide chemical industry depends on the transport of large quantities of liquid chemicals by maritime tankers. Chemical cargoes have different properties and many of them contain different hazards for both human life and marine environment. Even a small error, which will happen on a chemical tanker and management process, can cause catastrophic consequences both for human life and marine environment. Turkish chemical tanker fleet has been growing twice for last three years and will be growing more than average growing size of all Turkish merchant marine fleet and world marine fleet by following years. This growing size constitutes its own risks. Therefore, Turkish chemical ship management companies need to be managed with strategic management principles. Strategic management consists with four main steps: first one is investigating the present situation; the second one is investigating where to go; third one is strategy making step: 'how to go' and last step is control and measurement step. Every organization and program constitute its strengths and weaknesses, opportunities and threats. Considering these strengths, weaknesses, opportunities and threats (SWOT), several strategies are derived for converting the threats into opportunities, and off-setting the weaknesses against the strengths. SWOT analysis is intended to maximize both strengths and opportunities, minimize the external threats, and transforms the identified weaknesses into strengths and to take advantage of opportunities along with minimizing both internal weaknesses and external threats. SWOT Analysis is one of the best ways for observing present situation during strategic management process. Therefore, SWOT Analysis method is used for investigating the present situation and Analytical Hierarchy Process (AHP) method is used for weighting the SWOT factors. Analytical Hierarchy Process is a mathematical model that is used for solving decision problems. AHP can deal with qualitative attributes as well as quantitative ones. By utilizing AHP, relative priorities of factors can be obtained. By utilizing the AHP in SWOT analysis, individual SWOT factors can be weighted and rated quantitatively. In this paper, present situation of world and Turkish chemical fleet is investigated with all details; positive and negative factors that are affecting the chemical tanker management processes observed with SWOT analysis method and these factors are weighted with AHP method for observing the priority of factors. According to the SWOT-AHP application results, most common strengths for Turkish chemical tanker management companies are present training institutions and inspection of chemical tankers continuously; weaknesses are inadequate human resources, inadequate training, fatigue of seafarers and inadequate organisational structure; opportunities are ergonomic design of new-built ships and developing technologies which are affecting ship management processes positively and threats are worldwide officer shortage, increasing ship management, fuel and ship construction costs and inadequate coordination between Turkish chemical tanker management companies. When the chemical tanker management company divided into three parts as commercial management part, technical management part and ship part, the ship is more affected from weaknesses and threats rather than other parts. According to observed weaknesses and threats, detailed model strategies produced for converting the present weaknesses into strengths and present threats into opportunities. These model strategies are: consisting appropriate management structure for chemical tanker management company; application of fuzzy logic multi criteria decision making models for chemical tanker selection and investment case problem for a ship owner; Application of fault tree analysis (FTA), event tree analysis (ETA) methods for chemical tanker processes and case accident investigations and proposed critically analysis based corrective actions according to these observations; Created software named as 'Seafarer evaluation and training software' (SETS) which can evaluate seafarers' performances quantitatively and recommend individual training programs for each seafarers. The main aim of this study is constructing strategic management structure for Turkish chemical tanker management companies and consequently creating safer, environmentalist and profitable chemical tanker shipping in Turkey by utilizing developed strategies which are developed in this study. Keywords: Shipping business, strategic management, SWOT-AHP
Statistical evaluation of the carbonization results of hazelnut shell
Get PDFÇalışmada, farklı karbonizasyon koşullarının katı ürün verimi üzerine olan etkisini belirlemek amacıyla, fındık kabuğunun (Corylus Avellana) karbonizasyonu gerçekleştirilmiş ve sıcaklık, ısıtma hızı ve tanecik boyutunun karbonizasyon katı ürün verimi üzerine olan etkileri araştırılmıştır. Karbonizasyon deney sonuçları, iki seviyeli faktoriyel tasarım matrisine göre, istatistiksel olarak değerlendirilmiştir. Karbonizasyon deneyleri, sabit yataklı Jenkner tipi retort kullanılarak, statik gaz atmosferinde gerçekleştirilmiştir. Karbonizasyon sonucu elde edilen katı ürünün verimini en fazla etkileyen parametrenin, karbonizasyon sıcaklığı olduğu belirlenmiştir. Karbonizasyon sıcaklığından sonra sırasıyla, tanecik boyutu ve ısıtma hızı da katı ürün verimini etkilemektedir. Katı ürün verimi, artan sıcaklık ve ısıtma hızıyla azalırken, artan tanecik boyutuyla birlikte artış göstermiştir. Statik gaz atmosferinde yürütülen karbonizasyon deneyleri sonucunda, en yüksek katı ürün verimine sıcaklığın 723 K, tanecik boyutunun 1-1.4 mm ve ısıtma hızının 5 K/dak olduğu koşullarda ulaşılmıştır. Çalışmada, faktoriyel tasarım tekniğiyle, karbonizasyon sonucu oluşan katı ürünün verimini etkileyen parametrelerin istatistiksel olarak değerlendirilmesi yanında, ayrıca, fındık kabuğu ve karbonizasyon sonucu en yüksek verimde elde edilen katı ürünün, kısa analiz ve ısıl değer sonuçları karşılaştırılmış ve katı ürünün ısıl değerinin ve sabit karbon içeriğinin fındık kabuğuna kıyasla arttığı, uçucu madde içeriğinin ise azaldığı gözlenmiştir. Sonuç olarak, karbonizasyon sonucu elde edilen katı ürünün, yüksek enerji içeriğine sahip, çevreye dost, katı bir yakıt olarak değerlendirilebileceği belirlenmiştir. Anahtar Kelimeler: Biyokütle, karbonizasyon, faktoriyel tasarım, fındık kabuğu.Carbonization experiments has been conducted on the samples of hazelnut shell (Corylus Avellana) to determine the effect of carbonization variables such as temperature, heating rate, and particle size on the biochar yield. A statistical design technique was applied by use of a two-level factorial design matrix to interpret experimental results. Carbonization experiments were carried out at a static gaseous atmosphere in a Jenkner type fixed bed retort system which is a cylindrical stainless steel fixed bed reactor with a length of 270 mm and an inner diameter of 130 mm. The reactor was heated externally by an isolated electrical furnace where temperature was measured by a Ni-Cr-Ni thermocouple inside the bed. During the carbonization the inner and outer temperatures of the reactor were controlled continuously with a temperature control instrument. Before heating, the system was flushed with dry nitrogen for 30 minutes to remove all traces of oxygen. After carbonization at final temperature which lasted 30 minutes, the final weight of samples was determined to calculate the biochar yield. It was found that the biochar yields of samples were changed depending on the carbonization conditions. Amprical relations between the biochar yield and the carbonization conditions were developed. Biochar yield of hazelnut shell was decreased with the increasing temperature and heating rate and increased with the increasing particle size. The regression equation clearly showed that since the coefficient of temperature is the highest among all the variables, the effect of this variable on the char yield is the strongest. The decrease in the char yield at the higher temperature is connected with secondary decomposition of the char and this situation is consistent with the increase in the volatile matter. The heating rate affects the amount and rate of volatile matter evolution from the sample during carbonization. The increase in the rate of volatile matter evolution also prevents the formation of further reactions which increase the char yield. An increase in heating rate decreases the restricted effects of mass transfer and increases the decomposition of the biochar into liquid and gas product. Contrary to the effect of the temperature and heating rate, particle size variable has a positive influence on the the biochar yield values which means that biochar yield values are increased with increasing particle size and decreased with decreasing particle size. A possible reason for the observed decrease in biochar yield with decreasing particle size could be that smaller particles are heated more uniformly and thus heat and mass transfer are facilitated. This results in a higher mass loss and reduction in biochar yield. Larger particles may cause higher heat transfer resistance that results in lower interparticle temperatures and lower volatile evoluation. The higher the volatile residence time in the larger particles can result the greater possibility of secondary reactions. By taking into account the above results, the optimum carbonization conditions for maximum biochar yield were determined as T=773 K, Rt=5 K /min and Dp=1-1.4 mm. The raw material and biochar product obtained at maximum yield condition were characterized and compared according to their fuel properties. For this purpose gross calorific value and proximate analysis of samples were performed and compared. The raw material has very high volatile matter and very low ash value. Biochar obtained in this study is a carbon-rich fuel and contains 6.58% ash, 30.26% volatile matter, and 63.16% fixed carbon. In comparison with raw material, biochar sample can be characterized as carbon rich solid fuel with high content of fixed carbon and low volatile matter content. Gross calorific values of raw material and biochar samples were found as 18.33 MJ kg-1 and 29.08 MJkg-1, respectively. Biochar has a higher calorific value than the apricot stone due to its low moisture and high fixed carbon content. This study proved that experimental design methodology could efficiently be applied for evaluation of analytical parameters affecting biochar yield and that it is an economical way of obtaining the maximum amount of information in a short period of time and with the few number of experiments. Moreover, this study shows that the hazelnut shell can be a resource for biochar production. After further investigations, biochar can be used for various industrial processes. High amount of hazelnut shell can be obtained in Turkey. Not only hazelnut shell but also other shells can be used as a resource of carbonization for production of alternative fuels and activate carbon. It can be concluded from the overall results of this study that carbonization creates a different application area for hazelnut shell. Anahtar Kelimeler: Biyokütle, karbonizasyon, faktoriyel tasarım, fındık kabuğu
Combination of geodetic techniques in monitoring of engineering structures
Get PDFBu çalışmanın amacı, İstanbul’un güneybatısında, Büyükçekmece Gölü üzerinde yer alan ve TEM (Transit Avrupa Otoyolu - Transit European Motorway) otobanının bir bölümünü oluşturan Karasu viyadüğünün deformasyonlarının GPS ve nivelman ölçmeleri ile araştırılmasıdır. Bu amaçla altı aylık periyotlarla iki yılda gerçekleştirilen ölçme kampanyalarından elde edilen veriler değerlendirilmiştir. Deformasyonların bir boyutlu (1B) (düşey) analizlerinde, öncelikli olarak GPS ve nivelman ölçülerinden türetilen yükseklik farkları ayrı ayrı değerlendirilmiştir. Yükseklik farklarının birlikte değerlendirildiği 1B deformasyon analizinin sonraki bölümünde, GPS ve nivelman yükseklik farklarının birleştirilmesinde Helmert’in HELMERT ve Rao’nun MINQUE Varyans Bileşen Tahmini (VBT) yaklaşımları kullanılmıştır. Üç adımda gerçekleştirilen 1B deformasyon analizi sonrasında, yalnızca GPS ölçüleri kullanılarak S-transformasyonu uygulanmış ve viyadüğün olası deformasyonları bir kez de üç boyutlu (3B) olarak irdelenmiştir. Makalede, bu araştırmada uygulanan her bir deformasyon analizi yaklaşımının teorik yapısı da özet olarak verilmektedir. Çalışmanın sonuçlarında: Transit Avrupa Otobanının önemli bir bağlantı noktasında yer alan ve 2160 metre uzunluğundaki viyadüğün deformasyonlarının değerlendirilmesinin ve ortaya konmasının yanı sıra, büyük mühendislik yapılarındaki deformasyonlarının araştırılmasında uygulanacak ölçme ve analiz yöntemleri konusunda gelecek çalışmalara katkı sağlanması da amaçlanmıştır. Anahtar Kelimeler: GPS, nivelman, deformasyon analizi, Varyans Bileşen Tahmini, S-Transformasyonu.It has a considerable importance to have the movements of an engineering structure within certain limits for the safety of the community depending on it. To determine whether an engineering structure is safe to use or not, their movements are monitored and possible deformations are detected from the analysis of observations. An appropriate observation technique, which can be geodetic or non-geodetic (geotechnical-structural) according to classification in Chrzanowski and Chrzanowski (1995), is chosen with considering the physical conditions of the observed structure (its shape, size, location and so on), environmental conditions (the geologic properties of the based ground, tectonic activities of the region, common atmospheric phenomena around the structure and so on), the type of monitoring (continuous or static) and the required measuring accuracy for being able to recognize the significant movements. Until the beginning of the 1980's, conventional measurement techniques have been used for detecting the deformations in large engineering structures. After that the advances in space technologies and their geodetic applications provided impetus for their use in deformation measurements. GPS positioning technique has the biggest benefit of high accuracy 3D positioning; however, the vertical position is the least accurately determined component due to inherent geometric weakness of the system and atmospheric errors. Therefore, using GPS measurement technique in deformation measurements at millimeter level accuracy requires some special precautions, such as using forced centering equipment, applying special measuring techniques like the rapid static method for short baselines and designing special equipment for precise antenna height readings. In some cases, even these special precautions remain insufficient and hence, the GPS measurements need to be combined with another measurement technique to improve its accuracy in height component. In geodetic evaluation of deformations, static observations obtained by terrestrial and/or GPS technique are subject to a two-epoch analysis. The two-epoch analysis basically consists of independent Least Squares Estimation (LSE) of the single epochs and geometrical detection of deformations between epochs. Here, the aim is analysing 1D and 3D deformations of an engineering structure using GPS and levelling measurements data. During the 1D deformation analysis, three different approaches were performed separately. In the first and second approaches, height differences from precise levelling measurements and GPS measurements respectively were input in the analysing algorithm. In the third approach the combination of height differences from both techniques were evaluated for vertical deformation. While combining the two measurement sets, Helmert Variance Component Estimation (HVCE) and Minimum Norm Quadratic Unbiased Estimation (MINQUE) techniques were used. 3D deformation analysis only with GPS measurements was accomplished using S-transformation technique. The theories behind the used deformation analysis and variance component estimation methods are summarized in the chapters. Thereafter the optimal solution for combining the GPS and precise levelling data to improve the GPS derived heights and hence to provide reliable inputs via the optimal solution for the deformation investigations are discussed. The highway viaduct of which deformations were inspected in this study is 2160 meter long and crosses over a lake on 110 piers. It is located in active tectonic region very close to the North Anatolian Fault (NAF). With the aim of monitoring its deformations, four measurement campaigns including GPS sessions and precise levelling measurements were carried out with six-month intervals. The session plans were prepared appropriately for each campaign on a pre-positioned deformation network. The results of this study, experienced with measurements of the viaduct, are thought to be important remarks for deformation analysis studies using GPS measurements. As the first remark, GPS measurement technique can be used for determining deformations with some special precautions like using forced centering mechanisms to avoid centering errors, using special equipments for precision antenna height readings, using special antenna types to avoid multipath effects etc. However, even though these precautions are taken to provide better results in 1D and 3D deformation analysis, GPS measurements have to be supported with Precise Levelling measurements. Keywords: GPS, levelling, deformation analysis, Variance Component Estimation, S-Transformation.
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