Gülşah Sunal

Yüksek Lisans | 2023 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

Because of the drawbacks related with the current corneal transplantation techniques such as donor shortage, rejection or disease transmission risk, there is still an urgent requirement in order to produce new treatments for regenerating corneal tissue. Specially, it is also necessary to overcome the problems related with the blindness and vision losses originating from damage to corneal endothelium. By considering these, corneal tissue engineering might possess an encouraging potential to ensure alternative and innovative approaches toward the development of effective corneal tissue equivalents. Peptides allow to the creation of bi . . .omimetic and bioactive material surfaces, thus peptide-modified scaffolds have become a popular subject of research in tissue engineering. Herein, our objective was to synthesize the corneal endothelium tissue-specific peptides, to conjugate these peptides on created polyvinyl alcohol (PVA)-xanthan gum (XG) membranes, to characterize the peptide conjugation and also to define the influence of those peptide conjugated structures on cellular viability to utilize in corneal endothelium tissue engineering. Mevcut kornea transplantasyonu teknikleriyle ilgili donör eksikliği, ret veya hastalık bulaşma riski gibi dezavantajlar nedeniyle, kornea dokusunun rejenerasyonu için yeni tedavilerin üretilmesi için hala acil bir ihtiyaç bulunmaktadır. Özellikle, kornea endoteli hasarından kaynaklanan körlük ve görme kayıplarına bağlı problemlerin de üstesinden gelinmesi gerekmektedir. Bunları göz önünde bulundurarak, kornea dokusu mühendisliği, etkili kornea dokusu eşdeğerlerinin geliştirilmesine yönelik alternatif ve yenilikçi yaklaşımlar sağlama konusunda umut verici bir potansiyele sahip olabilir. Peptitler, biyomimetik ve biyoaktif malzeme yüzeylerinin oluşturulmasına izin verir, bu nedenle peptid ile modifiye edilmiş yapı iskeleleri, doku mühendisliğinde popüler bir araştırma konusu haline gelmiştir. Burada, amacımız, kornea endoteli dokusuna özgü peptitlerin sentezlenmesi, bu peptitlerin oluşturulan polivinil alkol (PVA)- ksantan sakızı (KS) membranları üzerine konjuge edilmesi, peptit konjugasyonunun karakterize edilmesi ve ayrıca kornea endotel doku mühendisliğinde kullanım için bu peptit konjuge yapıların hücresel canlılık üzerindeki etkisinin tanımlanmasıdır. İlk olarak, geliştirilen PVA-KS membranlar üzerindeki peptit konjugasyonunu doğrulamak için, peptit konjuge numuneler Taramalı Elektron Mikroskobu (TEM), Enerji Dağılımlı X-Işını Spektroskopisi (EDX), Fourier Dönüşümlü Kızılötesi Spektroskopisi (FTIR) ve X-ışını Fotoelektron Spektroskopisi (XPS) analizleri ile karakterize edildi. Mevcut çalışmanın karakterizasyon sonuçları, sentezlenen peptitlerin PVA-XG membranlara başarıyla konjuge edildiğini gösterdi. Ayrıca, bu peptit ile modifiye edilmiş membranların insan kemik iliğinden türetilmiş mezenkimal kök hücrelerin (iMKH'ler) canlılığı ve çoğalması üzerindeki etkisi, MTT analizi ve Canlı/Ölü boyama tahliline göre değerlendirildi. Hücre canlılığı deneylerinin bulguları, geliştirilen peptit konjuge membran yapılarının iMKH'ler üzerinde toksik bir etkiye neden olmadığını ortaya koydu. Genel olarak, bu çalışmanın sonuçları, biyoaktif peptit modifiye PVA-XG membranların, kornea endoteli doku mühendisliği için kullanılma potansiyeline sahip olduğunu göstermiştir. Ayrıca, bu tez çalışmasının bu tür sonuçlarının kornea endotelinin rejenerasyonu ile ilgili daha sonraki araştırmalara yardımcı olacağına ve ışık tutacağına kuvvetle inanılmaktadır Daha fazlası Daha az

Atalay SEÇER

Yüksek Lisans | 2023 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

The way a droplet behaves when it lands on a surface depends on the characteristics of the surface and the flow conditions of the droplet. It can deposit, rebound, splash, etc. There is delimited research on how surface roughness and chemical composition affect the deformation of droplets upon impact, in comparison to the studies done on smooth surfaces. Our model uses two-phase flow to simulate the axisymmetric motion of droplets over surfaces with heterogeneities by combining the Navier-Stokes equations for motion with the Cahn-Hilliard equation for tracking the phase-field. We integrate the problem with a finite element solver (F . . .EM). To accomplish this, we use piecewise linear, 𝑃1, triangular finite elements for the pressure components, and piecewise quadratic, 𝑃2, for the velocity, phase field and chemical potential, in order to integrate the governing equations. We not only discuss the interpolation types of viscosity and phase field but also suggest a new quadratic interpolant for fluids. As a starting point, we examine the effect of droplets impacting onto smooth and chemically uniform surfaces, and compare our findings with experimental results to validate our solver. We show how the maximum spreading diameter, 𝑑𝑚𝑎𝑥, after impact scales over uniform energy surfaces and compare with the literature. Dimensionless parameters Weber, Reynolds, Cahn, Capillary, Peclet numbers and density with viscosity contrasts decide the outcome on the surfaces, however, by manipulating surface energy, it is possible to control the deformation of impacting droplets, even when other parameters are held constant. We designed a wettability pattern, added roughness and observe we could change the fate of an impacting drop Daha fazlası Daha az

Şen, Hayrettin

Yüksek Lisans | 2016 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

This thesis presents both control of mobile robots that can move by using collective motion algorithm and simulation of the robots during the motion. The orientation of the robots was controlled remotely by one user during the collective motion. The transmission of orientation data from the remote controller to the robots was done by using XBee modules. The control algorithm of collective motion was developed by using individual-based model. Two modes are considered during the control. These modes are search and swarm mode. The collective motion was performed by robots that are moving with respect to some pair-wise interactions. Th . . .e pair-wise interactions between the robots were proposed based on three rules namely attraction, parallel orientation and repulsion fields rules. While the mobile robots try to move toward their neighbors in attraction field, they try to remain close to their neighbors in parallel orientation field. The repulsion field rule avoids the collision with each other during the collective motion. Since the commercial mobile robots which can be used in swarm robotics are very expensive, the robots used in this study were manufactured in the Prototyping Laboratory, in Izmir Katip Çelebi University. The mechanical parts of mobile robots were designed using SolidWorks and manufactured by using 3D printer technology. Arduino Mega 2560 programmable board was used as control unit of the robots. One electronic circuit, named Arduino Shield Circuit was designed using Proteus 8 Professional. It was produced in order to connect the used electronic components to related pins on Arduino Mega 2560 easily and in a secure way avoiding short circuits. The simulation code works as a real-time simulation. The code uses the data received from the robots to simulate the motion of the robots. The simulation also saves the all the received data from the robots to one Excel file. Two parameters, polarization and expanse were calculated in order to observe and characterize the motion of the swarm robots by using the saved data. Lastly the collective motion was tested for a group of two, three, four and five robots. The expanse and polarization values were presented for each test Daha fazlası Daha az

Yazıcı, Mustafa Volkan

Yüksek Lisans | 2018 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

This thesis focuses on a Multileaf Collimator design that can shape the beam contour to fit the shape of target geometry and its design improvements. Main purpose of this design is lowering the number of leaves on the multileaf collimator and making the system easier to be controlled. As the Collimator devices undertake the most important point of the beam shaping procedure, ease of control and precision of collimator devices are the major points of operation. As the radiation therapy is one of the most complex and vital medical operations, this thesis started with the deep literature survey that formed the main constraints and goa . . .ls of the study. Additional constraints and goals were formed after the examination of commercial purpose collimators with respect to their advantageous and disadvantageous sides. Collimator devices either primary or secondary are integratedly used with Linear accelerators thus, linear accelerator devices were taken as another important factor that formed the constraints of design. First design of the collimator mechanism was started with the type and number synthesis. After this procedure, collimator mechanism was decided to be four degree of freedom decoupled manipulator that works in Cartesian coordinate system. After the main design was finished, study of the kinematic analysis of the decoupled mechanism was performed. Due to the fact that radiation therapy robot manipulators carry the collimator mechanisms and motion of the overall system may generate high inertia forces, weight of the collimator mechanism and footprint of the collimator mechanism were also aimed to be reduced. After the first design, upper jaws were modified to be work in polar coordinates instead of cartesian coordinate system. This modification was not only reduced footprint of the device but also reduced scattering issues caused from angular relation between beam and leaf side surface. This modification followed by manufacturing of the first prototype. Examination of the first prototype gave the final shape to the constraints and goals to the collimator design as further advancing in weight and footprint reduction. By using these final constraints second modification was performed to the system and second prototype was manufactured Daha fazlası Daha az

Alpay Toprak

Yüksek Lisans | 2023 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

The design of a compound mobile serial robot controlled remotely by a C# program utilizing the MQTT (Message Queuing Telemetry Transport) protocol is the main topic of this thesis. The robot is powered by a Raspberry Pi. The advantages of mobility and serial manipulators are combined in the compound mobile serial robot, allowing it to carry out difficult tasks in a variety of settings. As the main computer, the Raspberry Pi gives the robot and its control application connectivity and processing capability. Data interchange and command execution are made possible by the integration of the MQTT protocol, which guarantees effective and . . . dependable connection between the robot and the control system. The integration of the MQTT protocol, hardware components, mechanical design, kinematic and dynamic analysis of the robot, and software implementation are all investigated in this study. This thesis intends to stimulate additional ideas in the field of intelligent and remotely operated robotic systems by utilizing the capabilities of Raspberry Pi and MQTT. For the protocol implementation, a 4 DoF serial arm and the mobile station connected to it were designed with mechanical design and prototype production was made, additionally direct and inverse kinematics of the robot arm has automatized with the C# WinForm application, thanks to this developed application, robot arm control was fully automatized and controlled. The thesis has demonstrated a novel applicacation of the protocol to a compound mobile serial robot, only there is no video for both mobile and serial robot arm working at the same time. Keywords: Compoun Daha fazlası Daha az

Manalp, Alpman

Yüksek Lisans | 2017 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

Medical imaging provides images of structures of the body that is not visible to human eye. It is a basic need that determines the irregularities, abnormalities, parts with different densities, spaces and foreign objects that is not supposed to be in the body. It has major importance for fast and correct diagnose. Imaging is frequently used for periodic scans for early diagnostic and follow up scans of treated patients. No matter how important it is, accessibility of the imaging devices especially digital imaging systems that provides real time images is extremely limited. There are very few of imaging device especially in co . . .untries with low income. The ratio between the number of equipment and population is so low compare to what it supposed to be. Equipment serves in very condensed and unsuited environments. Additionally, capability of maintenance and reparation are very limited. More than half of the population of the world cannot access to medical imaging facilities under current circumstances, even it is an emergency. Regardless of politic and geopolitical reasons, most important reason of this problem is lack of financial power to buy and maintain this equipment. In this study, an imaging device has been designed and a prototype has been produced using consumer electronic components. The cost of the designed system is only %0.2 of cheapest commercial alternative. Captured images have been compared with other commercial imaging equipment. It has been determined that the designed system is sensitive and capable enough to use for medical purposes Daha fazlası Daha az

Kemal Bartu Aydın

Yüksek Lisans | 2023 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

Today, with the developing telecommunications and electronic technologies for civilian and military purposes, electromagnetic (EM) applications have a wide usage area, including different frequency ranges, such as radar, wireless information transfer, and medical technologies, as well as radio frequencies. However, the broad use of these technologies causes EM wave pollution, so they have a devastating effect not only on the working functionalities of electronic devices but also on human health. Therefore, the need to develop these technologies to prevent EM wave pollution is increasing daily. In line with this need, numerous studie . . .s have been recently conducted to develop EM interference (EMI) shielding composite materials. Generally, it is aimed to achieve maximum absorption performance with minimum reflection to develop EMI shielding composites. On the other hand, the increase in the number of parameters affecting the performance of these materials also increases the time and cost required for experimental studies. In this case, mathematical and statistical approaches play a crucial role in contributing to experimental studies to reduce time and cost. iv In this thesis study, it is intended to develop a graphene foam/MnO2 nanowire composite structure as an EMI shielding material in order to apply a comprehensive design-modeling-optimization study to the field of materials science. In line with this aim, hydrothermal process parameters (temperature, time, molar ratio) were determined as the design variables of the optimization problem, and the effects of these parameters on the EMI shielding effectiveness (SE) of the nanocomposite structure were investigated. Moreover, the objective of the problem was defined as maximizing the absorption effectiveness of nanocomposite while conserving minimum reflection effectiveness. Data modeling processes were performed via a nonlinear neuro-regression approach to achieve a robust objective function for the defined optimization problem. In the optimization stage of this study, four different stochastic optimization algorithms (Simulated Annealing, Differential Evolution, Nelder-Mead, Random Search) were utilized simultaneously to obtain global optima. It is envisaged that this thesis study would make big contributions to the design-based optimization studies in the materials science subject Daha fazlası Daha az

Kemal Bartu Aydın

Yüksek Lisans | 2017 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

In recent years, laminated composites are fairly utilized in marine, automotive, aerospace, military and other engineering applications because of their high specific modulus (ratio between the young modulus and the density) and high specific strength (ratio between strength and density). In addition to these features, fiber reinforced composites have inherent tailorability such as fiber orientation and stacking sequence and provide great possibilities to designers against isotropic materials. Determination of the fundamental frequency performance of laminated composite plate is crucial for the design of the composite structures. Es . . .pecially, in dynamical engineering systems, fundamental frequency have to be taken into account in order to prevent resonance arising from external excitations. Laminated composite materials can fulfill this requirement with an appropriate stacking sequence by using optimization methods. In this thesis, the optimum designs of non-hybrid and hybrid laminated composite plates have been investigated. The considered laminated plate is simply supported on four sides. In non-hybrid cases, fundamental frequency is taken as objective function and fiber orientation angles of the laminated composites are taken as discrete and continuous design variables. The optimization has been conducted using graphite/epoxy, glass/epoxy and flax/epoxy materials for various aspect ratios (0.2-2). Single objective optimization formulation have been used for mathematical verification of model problems. In hybrid cases, multi objective approach is considered to maximize the fundamental frequency and minimize the cost simultaneously. The design variables of the multi objective optimization problems are selected as fiber orientation angles, the number of outer layers (No) having high-stiffness and more expensive and the number of inner layers (Ni ) having low-stiffness and inexpensive. Multi objective optimization has been carried out using hybrid graphite-glass/epoxy and graphite-flax/epoxy materials for various aspect ratios (0.2-2). Ecological approach in automotive, aerospace and marine industries have stated that natural fibers (especially flax) are of great importance for their use as alternative reinforcing materials to glass fibers because of their inherent good vibration and cost xii performances. In this regard, the present study is an attempt to show the usage of flax fiber as an alternative to E-glass in interply hybrid composite structures in terms of fundamental frequency and cost. Stacking sequences design and optimization of laminated composites based on Differential Evolution (DE), Nelder Mead (NM), Random Search (RS) and Simulated Annealing (SA) algorithms are considered. The results show that the proposed optimum graphite-flax/epoxy interply composite structure give better than the result of graphite-glass/epoxy in terms of maximum fundamental frequency and minimum cost. It is also found that DE, NM and SA algorithms show superior or at least comparable performance versus Ant Colony Optimization (ACO), Simulated Annealing (SA) and Genetic Algorithm (GA) in the literature for the same laminated structure design problems Daha fazlası Daha az

İbiş, Fatma

Yüksek Lisans | 2016 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

Hospital-acquired infections (HAI) (nosocomial infection) are serious health problems that occur when person acquires infection during stay in a hospital for causes other reasons than that infection. Colonization of microorganisms pave the way for deaths, in detail, Ventilator Associated Pneumonia (VAP) is remarkable in terms of mortality accounted for 15% of nosocomial infections. Ventilator associated pneumonia (VAP) is common a disease, especially among patients that are on connected ventilators in intensive care units. It is defined as the pneumonia, in which occurs in at least 48 hours after mechanical ventilation, is pr . . .ovided via endotracheal tubes or tracheostomy. This infection occurs because of assault of microorganisms that settle in endotracheal tubes in respiratory tract and then in lung parenchyma tissue. The most common settling organisms in respiratory tract are S.aureus, P. aureginosa, K. pneumonia, E.coli and Acinetobacter, Candida, Enterobacter species. Due to multi drug resistant microorganisms, the current treatments are inadequate and the mortality rate increases. Therefore, plasma can play significant role for the management of ventilator-associated pneumonia. Plasma is ionized gas and defined as the fourth state of matter. The treatments of plasma in health care can ensure quick and pretty effect to protect from resistant microorganism to antibiotics to patients. The purpose of present study is to develop a method of plasma treatment which can be utilized for the control and prevention of ventilatör associated pneumonia. For this concept, we have designed different systems and determined optimum parameters to prevent and eradicate biofilms of Staphylococcus aureus, Acinotabacter baumannii, Pseudomonas aureginosa, and Candida Albicans in endotracheal tubes. Our results indicate that, various plasma treatment modalities are capable of prevention and eradication of biofilms grown in endotracheal tubes. Therefore, cold atmospheric pressure plasma treatment methods could be considered as for the management of ventilator associated pneumonia Daha fazlası Daha az

Mülayim, Naciye

Yüksek Lisans | 2016 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

Nowadays, Expert System (ES)s are used widely in many areas to solve real world problems. Artificial Intelligence (AI) techniques are used to obtain timely and accurately decision about solution of daily problems in ESs designing because AI can mimic behaviours and thought system of people. Especially in medical area, there are many researches and applications using ESs based on various AI techniques to obtain diagnosis for any diseases. The liver is a vital internal organ for a human body and it has many functions, which are associated with the other organs. Although the liver can renew itself in the face of a damage and ¼ of live . . .r can even be enough for liver functions, a major damage is an obstacle for continual of the liver functions. For this reason, early diagnosis is very important in liver disorders. In this study, it was intended to generate expert systems based on Firefly Algorithm (FA) and Support Vector Machine (SVM) techniques for the diagnosis of liver disorders by using C# programming language and “Indian Liver Patient Dataset (ILPD)” and “Liver Disorder Dataset (BUPA Dataset)”. For performance evaluations of the proposed systems Accuracy, Positive Predictive Value, Negative Predictive Value, Sensitivity, Specificity, Precision and F-Measure were used. For ILPD, the proposed system based on Firefly Algorithm (FA) gave 92% Accuracy, 92% Sensitivity, 84.61 % Specificity, 95.91 % Positive Predictive Value, 83.01 % Negative Predictive Value, 95.91 % Precision and 93.91 % F-Measure. The proposed system based on Support Vector Machine (SVM) gave 78.33% Accuracy, 79.9% Sensitivity, 75% Specificity, 87.16 % Positive Predictive Value, 63.71 % Negative Predictive Value, 87.16 % Precision and 83.37 % F-Measure. For BUPA Dataset, the proposed system based on Firefly Algorithm (FA) gave 92.8% Accuracy, 96% Sensitivity, 90.66 % Specificity, 87.27 % Positive Predictive Value, 97.14 % Negative Predictive Value, 87.27 % Precision and 91.42 % F-Measure. The proposed system based on Support Vector Machine (SVM) gave 76.8 % Accuracy, 82% Sensitivity, 73.33% Specificity, 67.21 % Positive Predictive Value, 85.93 % Negative Predictive Value, 67.21 % Precision and 73.87 % F-Measure. It was clearly observed that the proposed system based on FA gave more successful predictions than the proposed system based on SVM in both liver disorders datasets and it is hoped that the generated systems will make contribution to in researches of expert systems based on artificial intelligence Daha fazlası Daha az

Marwan AL SAMAN

Yüksek Lisans | 2023 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

Bu çalışma temel olarak, Beton Plastikleşme Hasar modelinin (ing. Concrete Damaged Plasticity CDP) ve Değiştirilmiş Basınç Alanları Teorisi (ing. Modified Compression Field Theory, MCFT) formülasyonlarının doğrusal olmayan sonlu elemanlar yöntemine uygulanmasının etkinliğini değerlendirmeyi amaçlamaktadır. Farklı boyutlar, kullanılan çelik lif miktarı, beton dayanımı ve çekme donatısı oranı gibi geniş ölçekli değişkenleri kapsayan iki kiriş grubu üzerinde incelemeler gerçekleştirilmiştir. Birinci grup kirişler literatürden alınmış, ikinci grup kirişler ise İzmir Katip Çelebi Üniversitesi Yapı Mekaniği Laboratuvarında tasarlan . . .mış, imal ve test edilmiştir. Temel olarak gruplar, kirişlerin eğilmede veya kesmede kritik davranışa yol açacak tasarımlara sahip olmasına göre ayrılmıştır. Birinci grup, üçü çelik lifli ve ikisi lifsiz olmak üzere beş kiriş numunesinden oluşmuştur. Bu grup eğilmeye bağlı bir göçme tipine neden olacak şekilde tasarlanmıştır. İkinci grup kirişler ise, lif veya etriye içermediklerinde gevrek kesmeden kırılacak şekilde tasarlanmıştır. Yapılan deneysel ve sayısal çalışmalar yük-deplasman davranışı, süneklik ve hasar durumları bağlamında incelenmiş ve değerlendirilmiştir. Elde edilen sonuçlara göre, CDP modeli ve MCFT formülasyonu genel olarak eğilmede kritik kirişlerin davranışını belirlemede başarılı olurken, MCFT formülasyonu kesmede kritik olan kiriş davranışını yakalamada yeterli başarıyı gösterememiştir. This study mainly aims to assess the efficiency of implementation of Concrete Damaged Plasticity model and Modified Compression Field Theory formulations into the nonlinear finite element method. The investigation was carried out on two groups of beams in order to cover a wide range of geometry, amount of steel fibers used, concrete strength, and tensile reinforcement ratio. Beams of the first group were taken from the literature and the second group beams were designed, constructed, and tested at the İzmir Katip Çelebi University Structural Mechanics Laboratory. Basically, the groups were separated considering the behavior being either critical in flexure or shear. The first group consisted of five beam specimens, three including steel fibers and two w/o fibers. This group was designed to fail from flexure. On the other hand, the second group of beams were designed to fail from brittle shear when did not contain fiber or stirrups. An investigation and analyze was made on the load-deflection behavior, ductility and crack patterns for the conducted experimental and numerical work. According to the findings, the CDP model and MCFT formulations were generally capable of determining of the behavior of the beams critical in flexure while MCFT formulations provided limited accuracy to capture the shear-critical beam behavior. Daha fazlası Daha az

Müftüoğlu, Tevfik Denizhan

Yüksek Lisans | 2016 | İzmir Katip Çelebi Üniversitesi Fen Bilimleri Enstitüsü

The understanding of sediment transport with fluid in pipes is one of the important issues in hydraulics engineering. If the fluid velocity is lower than a critical value, a stationary cuttings bed develops, which may cause excessive head loss. In this study, a Fuzzy Logic (FL) model is developed to estimate stationary cuttings bed thickness inside the annulus. Experimental data is collected from literature in order to train proposed models. Results showed that the cuttings bed thickness could be estimated using the developed model with a reasonable accuracy when compared with the experimental results. Also, the thickness of the sta . . .tionary bed can be estimated within an error range of ± 6.8 %, more accurately than the widely used models available in the literature Daha fazlası Daha az