Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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1-Octanol Dehydration on Al2o3-Sio2 Catalyst
(01. Izmir Institute of Technology, 2021-12) Uçar, Beyza; Şeker, Erol
Bu çalışmada, heterojen asit katalizörün 1-oktanol dehidrasyonunda, ürün dağılımına etkisi araştırılmıştır. Kullanılan katalizörler sol-jel yöntemiyle sentezlenmiştir. Sentezlenen katı asit katalizörler ağırlıkça farklı oranlarda (25%-75%, 50%-50% ve 75%-25%) Al2O3-SiO2 katalizörleriydi. Ayrıca, sentezlenen Al2O3-SiO2 katalizörlerin kalsinasyon sıcaklıkları 500 ̊C, 700 ̊C ve 900 ̊C idi. Bu çalışmanın amacı, Al2O3-SiO2 katalizörlerin asidik-bazik özelliklerini ve birincil alkol dehidrasyonu üzerindeki etkisini anlamaktır. Kullanılan bütün katalizörler için dehidrasyon reaksiyonu 150 ̊C ve reaksiyon süresi 4 saat olarak devam etti. Ürünler ve var olan miktarı GC-MS analizi ile belirlenmiştir. Buna ek olarak, katalizörlerin asidik ve bazik özellikleri NH3-TPD ve CO2-TPD analizleri ile açıklanmıştır. Ayrıca katalizörlerin kristalografisi, XRD sonuçlarına göre belirtilmiştir. Bu çalışma, katalizörlerin bileşiminin ve uygulanan kalsinasyon sıcaklıklarının, reaksiyon yollarını etkileyen asidik-bazik kuvvetleri üzerinde etkili olduğunu ortaya koymuştur. Bunun sonucunda ürün dağılımı ve genel dönüşüm değerlendirilmiştir. Ana ürünler oksalik asit 2-etilheksil tetradesil ester, oktil eter, esterler (Formik asit, oktil ester, Asetik asit, oktil ester ve Heptanoik asit, oktil ester) ve oktanal idi. Ürün dağılımının esas olarak Al2O3-SiO2 katalizörlerinin asidik ve bazik güclerine bağlı olduğu gösterildi.
3d Reconstruction Using a Spherical Spiral Scan Camera
(Izmir Institute of Technology, 2006) Vatansever, Mustafa; Aytaç, İsmail Sıtkı
Construction of 3D models representing industrial products/objects is commonly used as a preliminary step of production process. These models are represented by a set of points which can be combined by planar patches (i.e. triangulation) or by smooth surface approximtions. In some cases, we may need to construct the 3D models of real objects. This problem is known as the 3D reconstruction problem which is one of the most important problems in the field of computer vision. In this thesis, a sytem has been developed to transform images of real objects into their 3D models automatically. The system consists of a PC, an inexpensive camera and an electromechanical component. The camera attached to this component moves around the object over a spiral trajectory and observes it from different view angles. At the same time, feature points of object surface are tracked using a tracking algorithm over object images. Then tracked points are reconstructed in 3D space using a stereo vision technique. A surface approximation is fitted to this 3D point set as a last step in the process. Open source .Intel®-OpenCV. C library is used both in image capturing and in image processing.
3d-Printed Multiprobe Analysis System for Solar Fuel Research; Design, Fabrication and Testing
(Izmir Institute of Technology, 2016-12) Harmanlı, İpek; Karabudak, Engin; Ebil, Özgenç
Methods of generating electricity with unlimited, clean and cheap energy from solar energy are tried to be investigated and developed in practical and theoretical academic fields. Especially, photocatalytic water splitting (PWS) systems have been identified as the main method in this study as well as in many studies due to the advantages provided by production of solar fuels from water. In this research, a study was carried out on the alternatives of the both used experimental set-up and used photocatalytic material for PWS systems. A study has been carried out on both the used experimental setup and the used photocatalytic material alternatives in PWS systems. As an alternative experimental setup that allows small volume analysis for PWS by Unisense gas microsensors, a mini photoreactor was designed using 3-D drawing and printing techniques and its usability was tested for PWS applications. Moreover, some characterization results for the electronic band structure and the band gap of the lead (II) trioxovanadate (V) chloride [PbVO3Cl] crystal, which was discovered by Eanes and co-workers in 2007 at IZTECH, was introduced in this study by not only theoretical (DFT approximations; LDA, GGA and HSE06) but also experimental (XRD, Diffuse Reflectance Method- Tauc Plot, Raman Spectroscopy, Four Probe) methods. Also, its estimated theoretical price and its potential for future application in tandem solar fuel device as a photoanode in combination with Si photocathode was calculated and discussed. The results showed that the designed mini photoreactor system is an open to development apparatus that is suitable for PWS, besides, PbVO3Cl has an "indirect transition" band structure and a band energy of ~ 2.2 eV. Although it did not give an effective result in PWS applications done by the designed mini photoreactor, it can be said that it is a semiconductor which is worth studying and developing in detail for other researches in this field due to the compatibility of its band energy amount and optical properties for PWS.
Aas, Xrpd, Sem/Eds, and Ftir Studies of the Effect of Calcite and Magnesite on the Uptake of Pb2+ and Zn2+ Ions by Natural Kaolinite and Clinoptilolite
(Izmir Institute of Technology, 2005) Zünbül, Banu; Shahwan, Talal; Shahwan, Talal
In this study, the effect of magnesite and calcite on the uptake of lead and zinc ions by mixtures of these carbonates with kaolinite and clinoptilolite was investigated at various loadings and mixture compositions. The concentration of both ions in the liquid phase was in measured using AAS, while XRPD, SEM/EDS, and FTIR techniques were used in characterizing the solid samples. Thestudy included the determination of kinetics and sorption isotherms of lead and zinc on pure kaolinite and clinoptilolite. Moreover, the sorption behavior of lead and zincat different concentrations and pH conditions was investigated on mixtures of calcite and magnesite with kaolinite and clinoptilolite at carbonate mass percentage compositions of 5, 10, 25, 60 in addition to pure calcite and magnesite. The morphologies of theformed precipitates, the plausible structural change in the lattice of calcite, magnesite, kaolinite, and clinoptilolite originating from sorption of lead and zinc ions was examined. According to obtained results, the sorption affinity of kaolinite and clinoptilolite towards lead is larger than their affinity towards zinc. Within the operating experimental conditions, the sorption capacity increased with increasing the amountsof calcite, and magnesite. The overall order of retention of lead and zinc was observed as magnesite . calcite> clinoptilolite> kaolinite under neutral and alkaline pH conditions and high loadings. When the initialconcentration of zinc and lead ions is raised to saturation conditions, rapid overgrowth of cerussite and hydrozincite was observed. Increasing the initial pH to 10,0 causedenhancement in the dissolution of calcite and magnesite, leading to the enhancingthe precipitation of hydrozincite, and an increased formation of hydrocerussite instead ofcerussite. The uptake of Zn2+ and Pb2+ions by calcite and magnesite have lead to modifying the geometry of the carbonate groups, the thing reflected as variation in their vibrational bands.
Abelian-Non Abellian Mixing and Cosmic Inflation in Born-Infeld Type Gravity
(Izmir Institute of Technology, 2013) Altaş, Aslı; Demir, Durmuş Ali
General Relativity (GR), which forms the basic framework for understanding cosmological and astrophysical phenomena, is based solely on general covariance. Therefore, the theory admits extensions regarding various phenomena related to inflation, massive gravity, dark energy etc. In this thesis work we study Born-Infeld type extensions of the GR. There are mainly two parts in the thesis: The extension based on Ricci tensor (already known in literature) and a novel extension based on Riemann tensor. We call them respectively Born-Infeld-Einstein (BIE) and Born-Infeld-Riemann (BIR) extensions. The BIR formalism is being proposed and studied in this thesis work. In a comparative fashion, we study these two extensions for determining their implications for 1. Mixing between Abelian and Non-Abelian gauge fields, and 2. Inflationary phase of cosmic evolution. As we prove explicitly, the two approaches yield distinct predictions for these phenomena. We emphasize that a slow-roll inflationary dynamics is naturally realized in BIR. The mixing between Abelian and Non-Abelian sectors enables cosmic photon production in inflationary phase.
Accelerometer Based Handwritten Character Recognition Using Dynamic Time Warping
(Izmir Institute of Technology, 2016-07) Tunçer, Esra; Ünlü, Mehmet Zübeyir
Character and gesture recognition are one of the most studied topics in recent years. Character recognition studies are generally based on image processing. Only a few studies can be found about character recognition as gesture recognition. Gesture recognition is making the computers understand human body movements by using different kind of knowledge of the environment. This knowledge can be obtained by image or sensor-based efforts. Accelerometer is the most used sensor in gesture recognition, so in this study a 3-axis accelerometer is used. In this thesis, English alphabet‟s lowercase characters are used. A ring-like device which contains accelerometer in it is used. After obtaining the acceleration data of each character with 20 repetitions, we apply filtering, segmentation and normalization preprocessing steps for each signal. Since there are different accelerations and decelerations between each repetitions, Dynamic Time Warping (DTW) algorithm has been chosen to determine the similarities between signals. DTW is an algorithm that uses the amplitude values of the signals, so it is weak to amplitudes that shift in time domain. To overcome this shortcoming, the method called Derivative Dynamic Time Warping (DDTW) has been applied to the acceleration signals. DTW and DDTW methods have been compared and we have found that even we remove the normalization step; DDTW gives better results than DTW. By comparison of linear alignment and DTW, the results show that DTW gives better recognition rates for signals with different accelerations and decelerations. DTW also gives better result for the different length signals.
Access Monitoring System for Distributed Firewall Policies
(Izmir Institute of Technology, 2008) Çakı, Oğuzhan; Tuğlular, Tuğkan
Internet has provided several benefits in terms of information sharing. However, Internet is an insecure environment that can cause threats to private networks. As a result, network security becomes a critical issue. One of the important tools used in network security is firewall. Firewalls protect a private network from external threats by restricting network traffic according to predefined security rules. Basically, firewalls apply these rules to each packet that passes over them. Distributed firewalls are a new approach to firewall to overcome some drawbacks of traditional firewalls. Distributed firewall design is based on the idea of enforcing the policy rules at the endpoints rather than a single entry point to network. Management of policy rules is a critical issue in both traditional and distributed firewalls. We propose a monitoring application for distributed firewall policies to keep track of actions (create, read. update, delete) performed on policy rule set. The resulting data produced by the monitoring application will be very helpful in policy management process.
Acoustic Design Based on Multi-Aspect Performance Analysis
(Izmir Institute of Technology, 2013) Atça, Emre; İlal, Mustafa Emre
In current architectural practice, architects, due to time and budget constraints do not analyse their designs and evaluate alternatives from the building physics perspective. They expect this analysis to be carried out by engineers. Unfortunately, engineers mostly get involved late in the design process, after many key decisions are already finalized, leaving them powerless to solve problems employing efficient strategies. However, the rapid advances both in computing and engineering have produced various simulation based tools for evaluating building performance that architects themselves can employ in the early design stages. The proliferation of the utilization of these tools throughout the architectural practice and education is necessary for achieving higher performance levels in the built environment. In this study, the main Lecture Hall at Izmir Institute of Technology, Department of Mathematics is diagnosed and documented through measurements and the possibility of predicting this existing level of performance through simulations during the design stage is explored. The brand new Lecture Hall is in urgent need of renovations, with additional costs, in order to improve acoustic, visual and thermal comfort in the space. Architects need to follow a performance based design approach where they consider performance criteria and utilize building simulation tools for design support in order to avoid problems that introduce costs later in the construction and operation of buildings.
Acoustic Indoor Localization Employing Code Division Multiple Access
(Izmir Institute of Technology, 2010) Sertatıl, Cem; Altınkaya, Mustafa Aziz
Indoor localization becomes a demand that comes into prominence day by day. Although extensively used outdoor location systems have been proposed, they can not operate in indoor applications. Hence new investigations have been carried on for accurate indoor localization in the last decade. In this thesis, a new indoor location system, that aims to locate an entity within an accuracy of about 2 cm using ordinary and inexpensive off-the-shelf devices, has been proposed and an implementation has been applied to evaluate the system performance. Therefore, time of arrival measurements of acoustic signals, which are binary phase shift keying modulated Gold code sequences using direct sequence spread spectrum technique, are done. Direct sequence-code division multiple access is applied to perform simultaneous accurate distance measurements and provides immunity to noise and interference. Two methods have been proposed for the location estimation. The first method takes the average of four location estimates obtained by trilateration technique. In the second method, only a single robust position estimate is obtained using three distances while the least reliable fourth distance measurement is not taken into account. The system performance is evaluated at positions from two height levels using two sets of variables determined by experimental results. The precision distributions in the work area and the precision versus accuracy plots depict the system performance for different sets of variables. The proposed system provides location estimates of better than 2 cm accuracy within 99% precision. Eventually, created graphical user interface provides a user friendly environment to adjust the parameters.
The Activity of Silica Immobilized Palladium N-Heterocyclic Carbene Complexes Toward Mizoro-Heck Reaction and Their Characterization
(Izmir Institute of Technology, 2005) Aksın, Özge; Artok, Levent
C-C bond formation reactions are among the important processes in chemistry.A palladium-catalyzed reaction, commonly known as the Mizoroki-Heck (M-H) reaction, is a powerful method in construction of C-C coupling of olefins with aryl and vinyl halides.This thesis describes, mainly development and applications of novel silica anchored saturated molecular Pd-N-heterocyclic carbene (Pd-NHC) catalysts toward the M-H reactions of aryl halides.Characterization of the novel Pd-NHC complexes were performed using elemental analysis, NMR and X-ray crystallography techniques. The synthesized complexes were anchored over an amorphous silica surface through their triethoxy silane groups.On the basis of the results, the silica supported saturated Pd-NHCs were found to be highly active catalyst precursors for Mizoroki-Heck reactions of iodo- and bromoarenes with styrene and butyl acrylate olefins, when reactions were performed at 140 C in the presence of 1.5 molar equivalent Na2CO3 base. The catalyst preserved its original activity for 4-iodoanisole, 4-bromoacetophenone, 4-iodoacetophenone, iodobenzene and 4-iodotoluene reagents at least for 8 uses when Pd concentration, with respect to the aryl halide, was 0.5% in the reaction medium.The higher turnover frequencies were realized at the lower Pd concentrations. The AAS analyses revealed the presence of dissolved Pd species within the reaction medium at the early stages of reaction. Along with this finding, determination of Pd agglomerates onto silica surface by TEM examination indicates that the catalyst acted as a Pd reservoir and reactions were catalyzed homogeneously. In the course of reaction, Pd is liberalized to the solution involved with the reaction cycle and deposited onto silica surface to lead to form less active Pd agglomerates. That no trace of dissolved Pd was detected at the end of reaction by AAS is a positive finding for the purity of product.
Acylation of 2-Methoxynaphthalene Over Ion-Exchanged Beta Zeolite
(Izmir Institute of Technology, 2002) Kantarlı, İsmail Cem; Artok, Levent
Friedel Crafts acylation of 2-Methoxynaphthalene was carried out over various ion-exchanged . zeolites (Mn+., where Mn+: In3+, Zn2+, Al3+, Fe3+, La3+) with various anhydride (acetic, propionic and benzoic anhydrides), or acyl chloride (acetyl, propionyl and benzoyl chlorides) acylating reagents. The results suggested that selectivity towards the 6-substituted products was higher with the larger size anhydrides, propionic and benzoic anhydrides. The metal cation type within the zeolite significantly influenced the extent of conversion and product distribution. That La3+ exchanged zeolite displayed higher selectivity for the 6-position acylated product with anhydrides ascribed mainly to narrowing of channels by the presence of La(OH)2+ ions that leave no room for the formation of more bulky isomeric forms and to enhanced Bronsted acidity of the zeolite. With acyl chlorides, the recovery of ketone products was found to be remarkably low. 1-Acyl-2-methoxynaphthalenes actively underwent deacylation when acyl chlorides were used as the acylation reagent.
Adaptation of Digital Electronic Into Detector Systems Numexo2 in Exotic Nuclei Research
(Izmir Institute of Technology, 2017-07) Şahin, Elif; Demir, Durmuş Ali; Ertürk, Sefa
The main purpose of this thesis is to introduce and show the performance and capabilities of the newly developed digital electronic namely NUMEXO2, which has been tested, coupled with EXOGAM2 (EXOtic GAMma array) detector at GANIL in France. This electronic has been developed due to the necessity of high rate signal transferring capacity when a radioactive ion beam is applied in order to produce exotic nuclei and to understand their nuclear structure. NUMEXO2 will be used both with stable beam and radioactive beam experiment not only to have high rate digital experimental data during the experiment but also will be used to obtain good high resolution both for energy and time. In this thesis, we will try to explain the design, verification, and performance of the NUMEXO2. In order to show the performance of NUMEXO2, we will present the result from test experiment performed in France at GANIL, nuclear research centre.
An Adaptive Neuro-Fuzzy Approach for Modeling the Effects of Water-In Emulsion on Diesel Sprays
(Izmir Institute of Technology, 2016-09) Yavuz, Bekir Kağan; Rodriguez, Alvaro Diez; Saplıoğlu, Kemal
This thesis is prepared as an outcome of the Energy Engineering Master of Science program at Izmir Institute of Technology, IZTECH, in Turkey. The main purpose of this study is to analyse the effects of water content in diesel fuel spray behaviours using adaptive neuro-fuzzy inference system models (ANFIS) for compression ignition engines. The investigations are carried out using numerical models of ANFIS in MATLAB R2011a, generating simulations from training and test datasets based on recent experimental studies from the literature. The thesis primarily tests the use and the fitness of ANFIS models, modifying the neural network structure so that the simulations acceptably reach the experimental results accurately. Then secondarily, the simulation is used to investigate the effects of parameters originally not available in the related study. The investigation mainly focusses on water in diesel emulsions from pure diesel to an emulsion with 20% water content. Operational conditions such as chamber ambient pressure, injection pressure, chamber ambient temperature are also investigated to find their effects over spray penetration. It was found that the increase of water content in the diesel fuel did not have a relevant effect at very low and very high temperatures, however at medium-high temperatures it increased spray penetration. Furthermore, it was observed that the increase of chamber ambient pressure and chamber ambient temperature reduced the spray penetration as expected.
Adaptive Thermal Comfort Analysis of Historic Mosque: the Case Study of Salepçioğlu Mosque, Izmir, Turkey
(Izmir Institute of Technology, 2016-10) Bughrara, Khaled S. M.; Durmuş Arsan, Zeynep; Gökçen Akkurt, Gülden
Mosques differ from other types of buildings by having intermittent operation schedule. Due to five prayer times per day throughout the year, mosques are fully or partially, yet periodically, occupied. Historic mosques, possessing cultural heritage value, need to be evaluated in terms of thermal comfort. The adaptive thermal comfort method presented by ASHRAE 55 is recommended to be used to analyze thermal comfort conditions of unconditioned buildings. The aim of research is to analyze thermal comfort conditions of historic mosques throughout the year, and to conduct an adaptive comfort analysis. The selected Salepçioğlu Mosque was built in 1905 in Kemeraltı, İzmir, Turkey. The objective is to improve indoor thermal comfort levels by applicable interventions with specific attention to its heritage value. First, indoor and outdoor microclimate of Salepçioğlu Mosque was monitored from October 2014 to September 2015. The physical model of mosque was created via dynamic simulation modelling tool, DesignBuilder v4.2. The model was calibrated by comparing simulated and measured indoor air temperature within hourly error ranges defined by ASHRAE Guideline 14. Whole-year thermal comfort analysis was conducted on monthly basis by using adaptive thermal comfort model. The adaptive comfort analysis of monitoring campaign shows that the Mosque does not satisfy acceptable comfort levels. Different scenarios were applied to better comfort levels. The best improvement is obtained with underfloor heating by which discomfort hours drop into 1369 hours by 31.34%, while it was 3760 hours by 86.08% in the baseline model.
Adhesion of Dopa Functionalized Gels To Spin Labeled Surfaces
(Izmir Institute of Technology, 2017-07) Göksel, Yaman; Akdoğan, Yaşar; Emrullahoğlu, Mustafa
This study investigates the force free adhesive properties of synthetic polymer in aqueous media using electron paramagnetic resonance (EPR) spectroscopy. Due to poor performance of commercial adhesives in wet environments, scientists are interested in different types of adhesives to overcome this difficulty. On this context, mussels attract attention because of their versatile properties to adhere different types of surfaces from rocks to ship hulls underwater. Adhesion occurs when mussel secretes mussel foot proteins (MFPs) in order to form threads and plaques. Seven types of MFPs are unique in plaque contains high amount of L-3,4-dihydroxyphenylalanine (DOPA) amino acid which is reputed to be responsible for adhesion. In this research, branched polyethylene glycol (PEG) based polymers functionalized with DOPA were synthesized and their force-free adhesive properties to hydrophobic polystyrene and hydrophilic silica nanobeads were investigated in solution. These nanobead surfaces were conjugated with spin label molecules to probe adhesion dynamics using EPR spectroscopy. In addition, gel forms of polymers obtained using NaIO4, FeCl3 and Cr2O7 were used as adhesive materials for EPR measurements. All of these adhesive materials showed adhesion to spin labeled polystyrene (SL-PS) surface. However, non-DOPA containing PEG showed no indication of adhesion thus, demonstrating the importance of DOPA in wet adhesion. In addition, EPR results showed that DOPA based PEG polymers were unable to adhere to spin labeled silica (SL-SiO2) surface. This behavior was attributed to hydration layers around silica nanobeads. These layers formed around hydrophilic SiO2 surface prevent interaction between nanobead surface and polymeric material.
Adolescents' Uses of Urban Public Spaces: a Case in Menderes (izmir)
(01. Izmir Institute of Technology, 2021-12) Şahin, Fatma Nur; Şenol, Fatma
The study examines how adolescents use urban public spaces and what kind of urban spaces they want. It details the social and physical environmental characteristics affecting the uses of public spaces and user perceptions of 15-18 years old students in the central settlement of Menderes District of the Izmir Province. This is a critical subject needed for an investigation. Public spaces are one of the common areas for the socialization and personal development of adolescents. Various studies have determined that adolescents' use of public spaces (e.g., streets, squares, parks) has differences from the general public use. Adolescents use public spaces to improve their relations with their surroundings, socialize with their peers and participate in various activities. They participate in friend-group activities, such as talking, chatting, resting, having fun, spending time with friends, playing games, meeting, hanging out, and so on. Although there is an increasing number of studies abroad, there is an important literature gap about characteristics affecting adolescents' use of public spaces in Turkey. In addition to many social characteristics (such as meeting with peers, feel free), adolescents' perceptions of the physical characteristics of the built environment (such as being an accessible, natural, and clean environment) are some of the essential characteristics that shape their use of public space. For this reason, the needs of adolescents must meet to achieve the necessary gains to complete their social development healthily and become well-developed adults in the future. However, studies on spatial possibilities are lacking that allow the realization of activities that meet these needs. This study aims to determine the social and physical characteristics affecting adolescents' use and perceptions of public spaces. This thesis developed as research about 15-18 years old high school students about their preferences and usage experiences in urban public spaces in the city center of Menderes District of İzmir. The differences in the uses and preferences of adolescents in using public spaces should reflect in the physical designs and plans of residential areas. Finally, it develops recommendations and strategies for the physical design of the public open spaces for adolescents.
Adsorption Kinetics of Methane Reformer Off-Gases on Aluminum Based Metal-Organic Frameworks
(Izmir Institute of Technology, 2017-07) Angı, Deniz; Çakıcıoğlu Özkan, Seher Fehime
Over the last decades, with the development in industrialization, the combustion of fossil fuels has generated an increasing level of emission of greenhouse gases into atmosphere. Considerable efforts have been endeavored to advance alternative cleaner energy source to relieve the stress on environmental concerns and depletion of oil reserves. Hydrogen is regarded as an ideal clean energy carrier. A great majority of ultrapure hydrogen is produced by hydrogen rich steam methane reformer (SMR) off-gas mainly composed of 60-80% H2, 15-25% CO2, 3-6% CH4 and 1-3% CO, which severely requires an efficient separation and purification process associated with gas adsorption principle. A novel class of porous adsorbents known as metal-organic frameworks (MOFs) represent outstanding separation performance due to possessing large surface area and tunable pore size. Aluminum based metal organic frameworks (Al-TPA) are widely utilized in gas separation/purification applications due to its breathing characteristics by adjusting cell volume reversibly. The highest surface area of Al-TPA was found to be 1270 m2/g by performing solvothermal synthesis route. Diffusion studies of SMR off-gas components on the Al-TPA were carried out at different flow rates (80, 168 and 175 mL/min), temperatures (34, 70 and 100 °C) and concentrations (15 and 28%). High value of parameter L demonstrated that system was under kinetic control. The diffusivity values were found to be ranging from 5.73 x 10-13-8.04 x 10-13 for CO2, 5.03 x 10-13-6.64 x 10-13 for CH4, 1.36 x 10-12-1.56 x 10-12 for H2 and 1.01 x 10-13- 5.03 x 10-13 m2/g for CO respectively with increasing temperature.
Adsorption of Methane Reformer Off-Gas Components in a Column Packed With Cu, Al,ti and Zn Based Organic Frameworks
(Izmir Institute of Technology, 2016-12) Kanaltı, Gaye; Çakıcıoğlu Özkan, Seher Fehime
Within the past decade, CO2 emissions from fossil fueled power plants has accelerated rapidly as a result of the increase in energy consumption associated with industrial development all over the world. Beyond the necessity of reduction in CO2 emissions, concerning on the crude oil reserves depletion induced the urgent need of transition to more efficient, renewable, cleaner and cheaper fuel, hydrogen. In the world, most of the hydrogen is produced by hydrogen-rich stream methane reformer (SMR) off gas streams composed of 80-60% H2, 15-25% CO2, 3-6% CH4 and 1-3% CO, thereby separation of SMR components became more of an issue. In this study, adsorption based separation of SMR components were investigated in a column packed with copper (CuTPA, (SLang: 776 m2g-1)), aluminum (AlTPA, (SLang: 1330 m2g-1)), titanium (TiTPA, (SLang: 1835 m2g-1)) and zinc (ZnTPA, (SLang: 1023 m2g-1)) based organic frameworks (MOFs). The pure gas adsorption studies on equimolar CO2/H2, CH4/H2 and CO/H2 systems and the equimolar mixture of CO2/CH4 system were carried out and the experimental breakthrough curves were obtained at three different feed flow rates (10, 20 and 30 mL/min) at three column pressure (1, 5 and 10 bar) at 303 K. The highest adsorption capacities of all MOFs were achieved at 30 mL/min of feed rate and 10 bar operating pressure, at these conditions the non-adsorptive behavior of hydrogen on the aforementioned MOFs was ensured. The amounts of CO2 adsorbed were calculated as 1.61, 5.54, 5.20 and 2.11 mmolCO2/g, while adsorbed CH4 amounts were 1.50, 3.16, 3.25 and 1.90 mmol CH4/g and the adsorbed CO amounts were 1.47, 2.59, 1.91 and 1.83 mmol CO/g on CuTPA, AlTPA, TiTPA and ZnTPA, respectively. The highest selectivity for CO2 over CH4 was attained on TiTPA as 8.0 at 10 mL/min feed rate of CO2/CH4 mixture at atmospheric column pressure and 303 K. The experimental adsorption isotherms of SMR components were fitted well with Langmuir and virial models and the best fitted model parameters were evaluated for each MOF.
Adsorption of Olive Leaf Antioxidants on Silk Fibroin
(Izmir Institute of Technology, 2006) Bayçın Hızal, Deniz; Bayraktar, Oğuz
This study focused on producing protein based functional food with antioxidative and antimicrobial properties by adsorption of olive leaf antioxidants on silk fibroin. In accordance with this aim, extraction and adsorption of two most abundant polyphenols in olive leaves, oleuropein and rutin were studied. Furthermore, desorption studies were performed to increase the purity of polyphenols.In this study, effect of various parameters on extraction and adsorption were investigated by HPLC and antioxidant analyses. The adsorption isotherms of oleuropein and rutin were plotted at different temperatures, pH values and solid-liquid ratios. After adsorption, the adsorbed polyphenols on silk fibroin was subjected to SEM, FTIR, color, antioxidant and antimicrobial analyses to observe the changes in the silk fibroin.The experimental data of adsorption isotherms were well-fitted to Langmuir model. The maximum adsorption capacity was determined as 108 mg oleuropein/g silk fibroin and 21 mg rutin/g silk fibroin. In desorption process, 81% of rutin and 85 % of oleuropein were removed from the adsorbent surface in 70 % aqueous ethanol solution.After adsorption of oleuropein and rutin, the antioxidant capacity of silk fibroin increased from 1.93 mmol TEAC/g to 3.61 mmol TEAC/g. Silk fibroin also gained antimicrobial activity against Staphylococcus aureus and Klebsiella pneumoniae after adsorption of olive leaf antioxidants. Desorbed polyphenols exhibited higher antioxidant capacity than the same amount of olive leaf extract due to the increase in the purity of oleuropein and rutin after desorption.Consequently, silk fibroin is a promising protein for the production of functional food or dietary supplements and for the purification of oleuropein and rutin.
Aeg and Peter Behrens: Symbolism in the First Corporate Identity Design
(Izmir Institute of Technology, 2012) Boztepe, Uygar; Yücel, Şebnem
Some historians called Peter Behrens' designs for AEG as first corporate identity design without a detailed analysis. Another group of the historians claimed that his works for AEG were shaped by only function or machine-aesthetic. Even some of these historians saw Behrens' works as inceptors of functionalism or rationalism in modern architecture. This thesis attempts to fill the gap in literature by analyzing Behrens' works for AEG in order to understand whether his designs formed a corporate identity or not. In order to show the shortcomings of such readings, the thesis explores the symbols that were used in the designs of Behrens, even in his most-functionalist design-works. The discussion was carried out through analysis of Behrensâ€™ and his contemporariesâ€™ written and design works, with materials available in Klingspor, Mathildenhöhe and TechnikMuseum Berlin Archives. This analysis is done through a review of scientific management techniques and their reflections in architectural culture and by parallel readings of literature and architecture in Germany at the turn of the century. As the discussion of the thesis pointed out, Peter Behrens' designs for AEG can be called as first corporate identity design since they have a consistent design vocabulary. While designing for AEG Behrens used scientific management and mass-production techniques in his designs. However these were not the only forces that shaped his design-work. One can see the vestiges of the symbols in his works that are coming from literature and antiquity. The thesis argues that it is not possible to fully understand the architecture of Behrens without understanding symbols. The thesis hopes to make a new reading of modern architecture from a different point of view, which includes a discussion on symbolism in modern architecture, avoiding oversimplification and reductionism present in readings with functionalist focus.

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