Master Tezleri

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1-octanol dehydration on Al2O3-SiO2 catalyst
(Izmir Institute of Technology, 2021-12) Uçar, Beyza; Şeker, Erol; 01. Izmir Institute of Technology
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.
Air leakage detection in various cross sectioned air ducts and research on manufacturing methods for airtightness
(Izmir Institute of Technology, 2004) Aydın, Çiğdem; Özerdem, Mehmet Bariş
Air ducts and related equipments are important components of climate and ventilation systems in order to distribute clean air, necessary for the occupied space, to whole system and to control thermal comfort. Despite of Turkish standards on air duct are present, studies on energy consumption associated with air leakage are very rare in Turkey, on the contrary to many developed countries. In this study, the subject of preventing energy losses related to the leakage, which causes inefficient working condition, has been investigated. Firstly, air duct system and quality requirements have been explained and the main standards have been analyzed for airtightness of air distribution systems, as well. Secondly, duct system measurements have been conducted by choosing two different approaches. One approach covers leakage calculation of a single duct by using European Standard called Eurovent, whereas the other one divides the system into single sections and uses the Power Law Model for calculation of leakage occurred in each section.Single duct leakage measurements were made on 300 mm and 1000 mm diameter circular ducts and 300 mm by 250 mm and 1000 mm by 500 mm flanged joint rectangular ducts for positive internal pressures. Test results showed that duct leakage depends on the method of duct fabrication, method of sealing, workmanship and static pressure differential. Furthermore, calculated leakage factors were under the allowable leakage limits in classification .C. for rectangular and circular ducts that were produced by Venco A.Ş. Comparing rectangular to circular ducts both had the same length of seam and surface area; the leakage from circular ducts was less than 80% from rectangular ducts. The air leakage from all test ducts, with the same lock seam type, decreases, whereas the surface area increases.Branched duct leakage measurements were made on 300 mm and 630 mm diameter circular ducts and 300 mm by 200 mm and 500 mm by 300 mm rectangular ducts and also air distribution system for positive internal pressures. Test results showed that fittings in a system cause sudden changes in static pressure; therefore, duct leakage depends on fitting locations. The leakage rate in Spiro sealed system was less than 5% Trelleborg sealed system. The leakage measured in this study showed that seam leakage accounts from 14% to 20% of the total in the two rectangular ducts and from 8% to 13% for the round ducts with Pittsburgh and Spiral lock seams. These data show that the joints are the major source of duct leakage. Improvement in duct construction leading to duct systems with less leakage will need to focus on better joints. Keywords: airtightness duct system, air duct leakage, duct leakage model, ductwork test procedure and methods.
Airfoil boundary-layer stability calculations and transition prediction
(Izmir Institute of Technology, 2019-07) Pekdüz, Umut; Özkol, Ünver
This study involves research and understanding of airfoil laminar boundary-layer transition based on three codes in written FORTRAN: panel code, boundary-layer code and stability code, namely HSPM, BLP2D and STP2D. All codes were connected to each other via inputs-outputs in the one code, called as PBS code. Firstly, the inviscid pressure distribution was obtained using Hess-Smith panel method. Secondly, differential boundary-layer equations were solved for obtained inviscid pressure distribution from panel code. Thirdly, stability calculation was performed using obtained boundary velocity profiles from boundary-layer code at each streamwise stations. Finally, the onset of transition location was predicted using en method based on linear small-disturbance theory. The PBS code was first validated on NACA 0012 and NACA 0015 airfoils making comparison with an experimental work in literature. After validation, three different thick airfoils designed for wind turbine applications were analyzed in terms of lift coefficient and transition location, namely NACA 64-618, DU91W250 and DU4050. The results were compared with XFoil’s viscous and inviscid solutions and experimental measurements based on infrared thermography. It was seen that amplified disturbance frequency magnitude, amplification starting point and choice of threshold value are key points to correctly predict transition point for en method. Additionally, it was found that followings: First, as airfoil thickness increases, the need of interactive boundary-layer method increases for accurate lift coefficient; however, transition point can be still correctly predicted using inviscid pressure distribution. Second, at high angle of attacks and high Reynolds numbers, laminar boundary-layer separation point can be directly taken as transition point instead of using the en method.
Analysis of adhesively bonded composite aerospace structures developed by laser surface treatment
(01. Izmir Institute of Technology, 2023-06) Nuhoğlu, Kaan; Tanoğlu, Metin; Tanoğlu, Metin
Among the various joining techniques, adhesive bonding is a feasible alternative to mechanical fasteners to prevent incisions and discontinuity on aerospace structures. The performance of the bonded structures highly depends on the adhesion strength, which is directly related to the condition of the bonding surface. It is for this that laser surface treatment, a recently developing technique to improve bonding performance, has become suited for CFRP structures. Yet, predicting the failure strength and mechanism is vital for designing primary aircraft structures involving adhesively bonded composite structures. The scope of this paper consists of the validation and evaluation of adhesive bonding behavior in the case of joining between laser surface-treated CFRP structures, in particular, components of an aircraft wing box. To this end, both the experiment and numerical investigations of the secondary bonded coupons were examined. This study, in other words, includes experimentally revealing the bonding behavior through coupon and element-level mechanical test setups, as well as the simulation of those structures in the computer environment by performing FEA to predict the failure load and damage growth. In this regard, besides observing the effects of the laser surface treatment on the pure and mix-mode behaviors by means of the DCB, ENF, SLJ, and SSJ tests, identical specimens were numerically analyzed by utilizing macro-scale 2D and 3D models, employing the CZM technique. Meanwhile, a novel characterization study and the resulting TSL parameter identification method were achieved for an accurate numerical analysis. Eventually, in addition to the application methodology, the capabilities and appropriateness of the presented FEA method were discussed, comparing experimental and numerical results.
Analysis of electromechanical behavior of piezoelectric smart curved beams
(Izmir Institute of Technology, 2017-12) Aras, Tunç; Yardımoğlu, Bülent
In this study, electromechanical behavior of piezoelectric smart curved beam with variable radius of curvature is investigated using Finite Element Method. Firstly, a background of beam theories is provided as well as a discussion on the history of piezoelectric materials and the development of smart beams and smart curved beams. The deformations of curved beams, the differential equations for in-plane bending of curved beam with and without piezoelectric patch are presented. Finite element modeling of smart curved beam is done using ANSYS. The mesh size correctness and numerical accuracy is controlled by an equivalent straight cantilever beam having the same length, cross-section and loaded from its tip with the same amount of force that will be applied to the curved beam model. Tip displacement comparisons are done using an analytical and finite elements approach. The model is verified by comparing the analytical results of piezoelectric constitutive equations with results of finite elements method for a rectangular prism shaped piezoelectric patch. After the verification is complete, the consequent tip displacements on x direction and generated electric fields are observed after the loads of different magnitudes applied to the tip of piezoelectric curved beam. Finally, results are discussed.
Analysis of stochastic dynamical systems
(Izmir Institute of Technology, 2007) Güngör, Mesut; Savacı, Ferit Acar
In this thesis, analysis of stochastic dynamical systems have been considered in the sense of stochastic differential equations (SDEs). Brownian motion, which can be considered as a first example of stochastic dynamical systems, its derivation and its properties have been investigated, then the analytic and numerical solution methods of SDE have been studied with the examples from the physical world. In order to construct a random variable in a computer environment, random number generation algorithms have also been investigated. Finally a Matlab-Simulink block for numerical solutions of linear SDEs has been newly developed.
Analysis of the carcked infinite hollow cylinder with loading on crack surfaces
(Izmir Institute of Technology, 2009) Avcı, Fatih; Artem, Hatice Seçil
In this study, the cracked infinite hollow cylinder with an axisymmetric crack of width (b-a) is considered. The ring-shaped crack is located at the symmetry plane. Surfaces of the crack are subjected to the distributed compressive loads. The outer surface of the cylinder is rigid and the inner one is stress free. The material of the cylinder is assumed to be linearly elastic and isotropic. Integral transform techniques are used for the solution of the field equations. The resultant singular integral equation in terms of crack surface displacement derivative is converted to a system of linear algebraic equations by using Gauss-Lobatto, Gauss-Jacobi and Gauss-Laguerre integration formulas. The stress intensity factors at the tips of the crack are numerically calculated for uniform and linear load distributions on crack surfaces. Some results are presented in graphical and tabular forms.
Analysis of TNFRSF10B-As long-noncoding RNA's effects on various cancer cell properties
(Izmir Institute of Technology, 2019-12) Alkan, Ayşe Hale; Akgül, Bünyamin
Long noncoding RNAs (lncRNAs) being longer than 200 nucleotides constitute a different class of RNA molecules. Several studies indicated that they have regulatory role in cellular processes including cancer development. Some of them have exclusively high expression in particular cancer types and regulate certain cancer cell properties. This renders them potential biomarker or therapeutic target in cancer. In this study, effects of a candidate lncRNA TNFRSF10B-AS and lncCAMTA1 on cancer cell properties were investigated. Candidate lncRNAs from Doxorubicin, Fas mAB, TNF-alpha and Cisplatin treated HeLa cell line were chosen and their expression level was measured in different cell lines including healthy (BEAS2B and MCF10A), metastatic (H1299 and MDA-MB- 231) and non-metastatic cell lines (A549 and MCF-7) by qPCR. From a few candidates lncCAMTA1 and TNFRSF10B-AS were selected for further analysis. qPCR results obtained from comparison of different cancer cell lines showed that their expression differs at least in one comparison of cell lines. TNFRSF10B-AS silencing decreased proliferation of HeLa cells. lncCAMTA1 was silenced or overexpressed in HeLa cells but phenotypic effect couldn’t be detected by apoptosis and cell proliferation assay. Additionally, phenotypic effect also couldn’t be observed in other cell lines when TNFRSF10B-AS was silenced.
Analytical and numerical sensitivity analysis of constant temperature hot-wire anemometre
(Izmir Institute of Technology, 2014) Uz, Yusuf Can; Özkol, Ünver
Hot-wire anemometry (HWA) has been used for many years as a research tool in fluid mechanics. HWA consists of a wire sensor, a very fine element exposed to the fluid flow and of an electronic system, which performs the transformation of the sensor output into a useful electric signal. HWA is based on convective heat transfer from a heated wire which is placed into a fluid flow. The heat is generated inside the very fine wire owing to wire resistance when electrical current passes through it. Then, the wire will be subjected to heat losses by convection, conduction and radiation depending on the flow condition. To examine the theory of operation for the heated wire and plot the temperature distribution along it, energy balance for HWA is investigated by taking differential element of dx length of the filament. In order to understand static and dynamic characteristics of hot-wire, all kinds of heat transfer such as convection, conduction and radiation are taken into consideration. In present thesis, the static study starts to investigate influence of the sensor parameters on general behavior of the constant temperature hot-wire anemometer analytically and numerically at varying conditions. Most important part of this study is that the time dependent differential equation for the heated wire is solved to determine sensitivity of hot-wire by a perturbation method in the event of a harmonically changing heat transfer coefficient. Moreover, the influence of thin supporting wires, or copper plated wire ends, is evaluated to see the effects of them on sensitivity and heat dissipation to the prongs. Another important parameter for wire sensor is the aspect ratio (L/d). Aspect ratio affects the time constant, sensitivity and temperature distribution of heated wire; hence it needs to be examined. Also, effect of the various velocities on the temperature distribution and sensitivity along the hot-wire has been studied.
Analyzing social media data by frequent pattern mining methods
(Izmir Institute of Technology, 2018-07) Güvenoğlu, Büşra; Ergenç Bostanoğlu, Belgin
Data mining is a popular research area that has been studied by many researchers and focuses on finding unforeseen and important information in large dataset. Social media data is one of the most popular and large heterogeneous data collected from social networking sites, microblogs, photo or video sharing sites. Social media represents the entities and their relations. One of the popular data structures used to represent large heterogeneous data in the field of data mining is graphs. The nodes of a graph represent entities and the edges of a graph represent the relations between the entities. So, graph mining is one of the most popular subdivisions of data mining. A frequent pattern is referred to as pattern that is more frequently encountered than the user-defined threshold in a dataset. Frequent patterns in a dataset can give important information about dataset. Using this information, data can be classified or clustered. Frequent patterns can provide different perspective on social media data with respect to sociology, consumer behaviour, marketing, communities. In this thesis, popular frequent pattern mining algorithms have been examined and it has been observed that most algorithms are not suitable for large datasets. Since data in today’s world, especially social networks, has very large data, the existing pattern mining algorithms are not suitable for this data. The aim of this thesis is to implement an existing frequent pattern mining algorithm in parallel manner and to find frequent patterns in a social media data.
"ANN" artifical neural networks and fuzzy logic models for cooling load prediction
(Izmir Institute of Technology, 2005) Bozokalfa, Gökhan; Akkurt, Sedat
In this thesis Artificial Neural Networks (ANN) and fuzzy logic models of the building energy use predictions were created. Data collected from a Hawaian 42 storey commercial building chiller plant power consumption and independent hourly climate data were obtained from the National Climate Data Center of the USA. These data were used in both ANN and the fuzzy model setting up and testing. The tropical climate data consisted of dry bulb temperature, wet bulb temperature, dew point temperature, relative humidity percentage, wind speed and wind direction.Both input variables and the output variable of the central chiller plant power consumption were fuzzified, and fuzzy membership functions were employed. The Mamdani fuzzy rules (32 rule) in If .Then format with the centre of gravity (COG; centroid) defuzzification were employed. The average percentage error levels in the fuzzy model and the ANN model were end up with 11.6% (R2.0.88) and 10.3% (R2.0.87), respectively. The fuzzy model is successfully presented for predicting chiller plant energy use in tropical climates with small seasonal and daily variations that makes this fuzzy model.
The application of aliminum foam for the heat and noise reduction in automobiles
(Izmir Institute of Technology, 2005) Akseli, Ilgaz; Güden, Mustafa
An experimental study has been conducted to investigate the effective thermal conductivity and sound absorption coefficient of Al and SiCparticle/Al closed-cell foams.The foams were prepared using the foaming of powder compact processes developed by Fraunhofer CMAM. The foaming of powder compact process has been extended for the foaming of composite compacts containing 10 weight percent of SiC particles. Effective thermal conductivity measurements were performed using the temperature distribution for steady state conduction through a uniform plane wall method. The sound absorption coefficient measurements were conducted using the standing wave ratio method. The effect of hole drilling on the sound absorption coefficient of foams was also investigated. The measured effective thermal conductivities of the foams were also fitted to the previously developed effective thermal conductivity models of metal foams.The effective thermal conductivities of studied Al foams were then expressed as function of percent porosity with the best-fitted model equation. The effective thermal conductivity values of Al foams were also compared with those of Alporas closed and ERG open cell foams produced by the foaming of Al melt and investment casting methods, respectively. The sound absorption coefficients of Al and SiC/Al foams were found relatively low and similar at lower relative densities and frequencies. Hole drilling was found to be effective in increasing sound absorption values of foam above400 Hz. The sound absorption in Al and SiC/Al foams was further explained based on the viscous losses and thermal damping effects.
Bio-inspired design of a kinetic node for adaptable structures
(Izmir Institute of Technology, 2011) Acar, Melodi Simay; Korkmaz, Koray
The architectural design should no longer consider just in terms of today's demands, but also the life cycle and the further requirements of the built environment. The design process should consider the adaptation to the changing conditions which can be in terms of the building usage, environmental factors or even in the changes ofsociological demands. Rapid change in activities of modern society and building technologies, has led to the need for adaptable spaces. Those spaces can be obtained by the adaptable structures which have potential for using our resources in efficient way and also for responding to the era's needs. This can be achieved with kinetic structural systems and learning adaptable structures from nature.Nature has always inspired humanity by solving the basic needs with minimum material and sustainable solutions. Observation of nature enables architects and engineers familiar with highly developed structures and lead to the creation of new forms. The designs that are produced by learning from nature lead to practical engineering solutions in terms of sustainability. The aim of this research is to propose a joint; kinetic node with multidisciplinary approach. This kinetic node is designed by inspiring from the minimum energy shape configurations and the structural orders in natural structures especially the cell membrane and analyzing the joining details of space truss structural systems and the geometric principles of Bricard linkage mechanism. This new kinetic node gives capability to construct variable static and dynamic structural systems while constructing in different structural orders.
Capacitance-voltage spectroscopy in metal-tantalum pentoxide (Ta-O)-silicon mos capacitors
(Izmir Institute of Technology, 2005) Özdağ, Pınar; Güneş, Mehmet
The electronic properties of Al-Ta2O5-Si MOS capacitors with oxide layers prepared by RF magnetron sputtering with or without a prior nitridation process in N2O or NH3 gas environments at temperature ranges between 700 °C to 850 °C were investigated using Capacitance-Voltage (C-V) Spectroscopy to determine the quality of oxide layer and oxide-silicon interface. The theoretical ideal capacitance-voltage calculations were compared with the experimental capacitance-voltage results in order to evaluate effective oxide charges, Qeff , present inside Ta2O5 insulating layer and density of interface trap states, Dit, present at the Ta2O5-Si interface. In addition,dielectric constant, doping concentration, flat band voltage values were determined by using the experimental data. Finally, the effects of deposition conditions on Ta2O5 MOS capacitors were compared by using a reference sample of a MOS capacitor with native oxide SiO2. It has been found that dielectric constant value up to 12 have been reached for Ta2O5 insulating layers which increases the capacitance value several times than that of MOS capacitor with native oxide SiO2. The density of interface trap states, Dit, for unnitrided Ta2O5 MOS capacitors, values around 1.6x1012 cm-2 eV-1 have been detected which is much higher than that of MOS capacitor with native oxide SiO2. However, prior nitridation process enhances the interface properties and Dit values down to 2-5x1011 cm-2 eV-1 have been reached for the nitrided samples which is in the limits for MOS capacitors with high quality insulating layers. In addition, the effective oxide charges, Qeff, for unnitrided samples, values as high as 3x1012 cm-2 were detected. Even though nitridation process enhances interface properties, the effective oxide charges are found to be higher for nitrided samples. Best electrical and interface properties are obtained by nitridation process at 800 °C in N2O and NH3. It can be inferred that samples nitrided in N2O gas at 800 °C improves the dielectric constant above the level of SiO2 and decreases both Qeff and Dit levels to that of native oxide SiO2. These results show that a prior nitridation of p-silicon surface is a promising approach to improve both oxide and interface properties of Al-Ta2O5-Si MOS devices. However, further investigation is necessary to understand the nature of these oxide charges and interface properties of MOS devices with high dielectric constant oxide layers before integration into large scale fabrication.
Characteristics of limes produced from marbles and limestiones
(Izmir Institute of Technology, 2007) Toprak, Gülcan; Böke, Hasan
In this study, characteristics of lime produced from some marbles and limestones were investigated in order to compare their effects on the lime mortars. For this purpose, limestones that contain low and high amounts of diatoms and marbles quarried from the city of Muğla and the Marmara island were selected as samples. The calcination temperatures of the stones were found to be around 800 C by TGA analysis. Considering their calcination temperatures, they were heated to 850 C in a laboratory furnace, then slaked and carbonated. Before and after these processes, mineralogical and chemical compositions, and microstructures of the products were investigated by XRD and SEM-EDS analysis. The hydraulic properties of carbonated limes were evaluated by determining weight loss at the temperatures between 200-600 C due to the loss of the structurally bound water of hydraulic products and weight loss at the temperatures over 600 C due to carbon dioxide released during the decomposition of calcium carbonates by TGA. The effects of limes on the properties of mortars were investigated by producing lime mortars and comparing their compressive strengths during one year carbonation in laboratory condition. Mortars were prepared with one part (in weight) of lime and three parts (in weight) of marble aggregates. The results of the study indicated that the lime produced from limestone containing high amounts of diatoms is highly hydraulic due to formation of calcium silicate whereas the others are non-hydraulic. The mortars prepared from lime containing high amounts of diatoms were found to be relatively high in compressive strength due to its hydraulicity. The results show that the production of hydaulic lime composed mainly of calcium silicate at a relatively low calcinations temperature (850 C) is possible. Considering this result, it can be concluded that hydraulic lime could be produced by the calcining of limestone containing diatoms in historic kilns.
Characterization of connexin 26 mutations causing hereditary skin disorders
(Izmir Institute of Technology, 2013-06) Bay, Veysel; Meşe Özçivici, Gülistan
Connexins (Cx) are building blocks of gap junctions that provide intercellular communication between adjacent cells. There exist 21 types of connexins in human body which are important for human physiology. Hence, in any case of deficiency or mutation, disorders can occur. For instance, most of the characterized Cx26 mutations are related to deafness; while there are few mutations associated with different skin disorders. One of them is a rare congenital skin disorder; Keratitis- Ichthyosis-Deafness (KID) syndrome. In this study, we aimed to investigate the effects of Cx26 mutations associated with KID syndrome in two gap junctional communication-deficient cell lines; mouse neuroblastoma (N2A) and human cervix carcinoma (HeLa), and also in human keratinocytes (HaCaT). For this purpose, newly identified KID syndrome mutations, A88V, D50A, D50Y, and I30N were characterized. Studies on N2A cells demonstrated that Cx26 mRNA levels of mutants were higher than Cx26 WT, whereas their protein expression were very low compared to Cx26 WT. Moreover, in HeLa cells, mutant proteins were observed to be localized mainly in the cytoplasm. Furthermore, the uptake of fluorescent dyes into the cells through the mutant hemichannels was statistically higher than Cx26 WT hemichannels. For HaCaT cells, mutant proteins did not have any effect on Keratin 10 expression, a marker for suprabasal layers of epidermis. In conclusion, all four mutations caused increased hemichannel activity similar to other analyzed KID syndrome mutations, which provides a further support for the presence of increased hemichannel activity as a mechanism for mutations leading to KID syndrome.
Chemical composition analysis of agroindustrial waste and their potential usage in bio-ethanol production
(Izmir Institute of Technology, 2011) Üçüncü, Can; Tari, Canan
Between the year 2000 and 2008 the amount of fruits and vegetables used in fruit juice industry were 4918400 tons in Turkey. Thus, % 15-30 of a fruit is pomace, high amount of pomace appears as waste in fruit juice industry every year. Some of these pomaces could be candidates as potential fermentation media for bioethanol production. The aim of this study was in first step the optimization of the hydrolysis conditions using statistical methods and then the selection of the best hydrolysate for bioethanol production using the fungus Tricoderma harzianum. In the optimization study the factors were temperature, time, solid liquid ratio and acid percentage whereas the responses were furfural, hydroxymethylfurfural, glucose, xylose, galactose, arabinose and total reducing sugar yield. According to the results of the screening process, the hydrolysis step was carried out at a temperature and time of 126 ï‚°C, 40 min for apricot pomace and 110 ï‚°C, 40 min for peach and apple pomace. In the optimisation step and levels of the other factors were enlarged. The highest reducing sugar yield during optimization was 31% for apple, 49.16% for apricot and 52.44% for peach pomace. These results indicated that these pomaces hold certain potential for bioethanol production. Three different incubators (CO2, static and non-static) were used for the fermentation process. Tricoderma harzianum grown aerobically in two different media (YPM and YNB) inoculated in apple hydrolysates was used in each incubator for bioethanol production. The highest ethanol production was 1.67g/L in non-static incubator with the culture grown in YNB media.
Children's perceptions of neighborhood qualities: A case in Çorum (Turkey)
(01. Izmir Institute of Technology, 2021-12) Saraçer, Gizem; Şenol, Fatma; 01. Izmir Institute of Technology
Children's usage of open spaces is an important research field since it has several consequences on the healthy development of children. However, today most of the urban areas and particularly streets are designed for the use and needs of adults and cars. Moreover, there is an increasing shift in children's life from outdoor to indoor spaces resulted by the changes in the physical environment and parental safety perception. This study examines a group of 9-10 years old children's neighborhood perception in two neighborhoods in the central city of Çorum. It deploys an online parental survey, our site observations of physical characteristics of these neighborhoods, and a focus group interview with 22 children. This thesis aims to grasp physical and social factors of the neighborhood affecting children's usage of their immediate surroundings to improve children's active involvement in urban areas. Thus, strategies and recommendations are developed at the neighborhood level with the data extracted from field research to create child-friendly urban environments. According to the study findings, parental licenses are affected by social factors more than physical factors of the neighborhood. Besides, fear about strangers and vehicle traffic are the factors that cause parental restrictions at most. To create a child-friendly city, presence of other children in the neighborhood, suitable play equipment for different age groups, places for individual and group activities and mix land uses in the neighborhood are the common factors that emerged from the children's responses. Although parents and children give similar responses to the factors that negatively affect their perceptions, such as fear of strangers and inadequacy of green spaces, they have different expectations and concerns about their neighborhood. Therefore, the data obtained in this study highlight the importance of examining the different needs of children and parents at the neighborhood level in order to create child-friendly cities.
Comouter-aided aerodynamic design of small scale horizontal axis wind turbine blades
(Izmir Institute of Technology, 2012-07) Göçmen, Tuhfe; Özerdem, Mehmet Barış
In this thesis, aerodynamic design of 1, 5, 10, 25, 50, 100, 250 and 500 kW horizontal axis wind turbine generators has been performed. The design procedure starts with the design and analysis of airfoils done by programs of PROFOIL and XFOIL, respectively through which the structural, aerodynamic and aeroacoustic principles have been taken into consideration. Then, the performance parameters of designed profiles were inputted to the constructed modified blade element momentum theory (BEM) code together with the main design parameters in order to obtain 3D blade geometry. The code is validated using MIE wind turbine with a rated power of 8 kW. The generated blade geometries are then analyzed using commercial computational fluid dynamics CFD code Numeca FINEâ„¢/Turbo and the velocity and pressure distributions around the blade have been visualized, separately. Moreover, the power coefficient, Cp was calculated and the power curves of the designed wind turbine rotors were drawn.
Comparison of linear and cfd models with on-site wind measurement data for wind resource assessment
(Izmir Institute of Technology, 2014-01) Ay, Aytek; Özerdem, Mehmet Bariş
Wind resource assessment (WRA) estimates the strength of wind resources at a planned wind project site. The output of WRA is wind conditions and annual energy production at a wind project site. The aim of this study is to compare on-site measurements with a linear and non-linear flow model results by calculating the error values between and investigating the effects on the annual energy productions. Wind Atlas Analysis and Application Program (WAsP) is used for linear model approach, whilst software called WindSim is used for non-linear model approach based on computational fluid dynamics (CFD) concept. Relative and absolute wind speed errors which have been weighted with the frequency of the directions show that the CFD model gives better results. This non-linear model also leads in annual energy predictions with 1.8% relative error averaged over three met mast results which is 4.2% for linear model. Although non-linear results seem to be better in such a semi-complex site as a further study it is important to run several more test cases for sites with different complexity and stability conditions. The results of non-linear model have been obtained with a new post-processing tool created by Siemens Wind Power. It is also necessary to run the same calculation procedure for several more complex sites before using as a standard tool as this is the first test case of this calculation method.

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