Search results for: Aylin Sahin

Authors: Sahin Yakut, H. Kemal Ulutas, Deniz Deger

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Plasma Assisted Physical Vapor Deposition (PAPVD) method used to produce Poly(ethylene oxide) (pPEO) thin films. Depositions were progressed at various plasma discharge powers as 0, 2, 5 and 30 W for pPEO at 500nm film thicknesses. The capacitance and dielectric dissipation of the thin films were measured at 0,1-107 Hz frequency range and 173-353 K temperature range by an impedance analyzer. Then, alternative conductivity (σac) and activation energies were derived from capacitance and dielectric dissipation. σac of conventional PEO (PEO precursor) was measured to determine the effect of plasma discharge. Differences were observed between the alternative conductivity of PEO’s and pPEO’s depending on plasma discharge power. By this purpose, structural characterization techniques such as Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FT-IR) were applied on pPEO thin films. Structural analysis showed that density of crosslinking is plasma power dependent. The crosslinking density increases with increasing plasma discharge power and this increase is displayed as increasing dynamic glass transition temperatures at DSC results. Also, shifting of frequencies of some type of bond vibrations, belonging to bond vibrations produced after fragmentation because of plasma discharge, were observed at FTIR results. The dynamic glass transition temperatures obtained from alternative conductivity results for pPEO consistent with the results of DSC. Activation energies exhibit Arrhenius behavior. Activation energies decrease with increasing plasma discharge power. This behavior supports the suggestion expressing that long polymer chains and long oligomers are fragmented into smaller oligomers or radicals.

Keywords: activation energy, dielectric spectroscopy, organic thin films, plasma polymer

Procedia PDF Downloads 301

Authors: Emrah Ayhan, Puspa Saananta Irfani, Ömer Doğukan Şahin

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Public services, which are important for the order and continuity of social life, have begun to transform into electronic services (E-service) with the development of information and communication technologies in recent years. In particular, as a result of the widespread use of the internet and the increase in citizen demands, it has become necessary to provide public services electronically. In addition to facilitating traditional public services, new types of e-services strengthen the interaction, cooperation, accessibility, transparency, citizen participation (e-governance) and accountability between citizens and the state. In this context, the factors in the literature that are considered to influence the citizens’ satisfaction towards e-services will be examined through the example of student satisfaction with the e-services (Anasis, Mergen, E-mail, library, cafeteria and other transactions) offered by Anadolu University (Eskişehir, Türkiye) through university website and mobile application. The data for the analysis will be obtained from the survey research that will be used to measure user satisfaction with university e-services of 1,000 students studying at 9 different faculties and graduate schools of Anadolu University. These data will be analyzed with a unique methodology that uses the E-GovQual model and Importance Performance Analysis (IPA) methods together. The e-GovQual model serves as a framework for evaluating the quality of e-services, allowing a detailed understanding of students' perceptions. On the other hand, the IPA method will be used to determine the performance level of Anadolu University in the provision of e-services and to understand the areas that require improvement and student expectations. Strategic goals and suggestions will be made to decision-makers, students, and researchers in line with the findings obtained in the research. Thus, it is planned to contribute to e-governance and user satisfaction in educational institutions and to reveal practical implications for optimizing online platforms to better serve student needs.

Keywords: e-service, Anadolu university, student satisfaction, e-governance, e-govqual, importance performance analysis

Procedia PDF Downloads 57

Authors: Mustafa Tevfik Hebebci, Ismail Sahin, Sirin Kucuk, Ismail Celik, Ahmet Oguz Akturk

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ADDIE is an instructional design model which has the five core elements: analyze, design, develop, implement, and evaluate. The ADDIE approach provides a systematic process for the analysis of instructional needs, the design and development of instructional programs and materials, implementation of a program, and the evaluation of the effectiveness of an instruction. The case-based study is an instructional design model that is a variant of project-oriented learning. Collecting and analyzing stories can be used in two primary ways -perform task analysis and as a learning support during instruction- by instructional designers. Besides, teachers use technology to develop students’ thinking, enriching the learning environment and providing permanent learning. The purpose of this paper is to introduce an interactive online case-study library website developed in a national project. The design goal of the website is to provide interactive, enhanced, case-based and online educational resource for educators through the purpose and within the scope of a national project. The ADDIE instructional design model was used in the development of the website for the interactive case-based library. This web-based library contains the navigation menus as the follows: “Homepage”, "Registration", "Branches", "Aim of The Research", "About TPACK", "National Project", "Contact Us", etc. This library is developed on a web-based platform, which is important in terms of manageability, accessibility, and updateability of data. Users are able to sort the displayed case-studies by their titles, dates, ratings, view counts, etc. In addition, they encouraged to rate and comment on the case-studies. The usability test is used and the expert opinion is taken for the evaluation of the website. This website is a tool to integrate technology in education. It is believed that this website will be beneficial for pre-service and in-service teachers in terms of their professional developments.

Keywords: design, ADDIE, case based library, technology integration

Procedia PDF Downloads 479

Authors: Neslihan Sahin Celik, Ali Eraslan

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As a result of PISA (Program for International Student Assessments) survey that tests how well students can apply the knowledge and skills they have learned at school to real-life challenges, the new and redesigned mathematics education programs in many countries emphasize the necessity for the students to face complex and multifaceted problem situations and gain experience in this sense allowing them to develop new skills and mathematical thinking to prepare them for their future life after school. At this point, mathematical models and modeling approaches can be utilized in the analysis of complex problems which represent real-life situations in which students can actively participate. In particular, model eliciting activities that bring about situations which allow the students to create solutions to problems and which involve mathematical modeling must be used right from primary school years, allowing them to face such complex, real-life situations from early childhood period. A qualitative study was conducted in a university foundation primary school in the city center of a big province in 2013-2014 academic years. The participants were 4th grade students in a primary school. After a four-week preliminary study applied to a fourth-grade classroom, three students included in the focus group were selected using criterion sampling technique. A focus group of three students was videotaped as they worked on the Crime Problem. The conversation of the group was transcribed, examined with students’ written work and then analyzed through the lens of Blum and Ferri’s modeling processing cycle. The results showed that primary fourth-grade students can successfully work with model eliciting problem while they encounter some difficulties in the modeling processes. In particular, they developed new ideas based on different assumptions, identified the patterns among variables and established a variety of models. On the other hand, they had trouble focusing on problems and occasionally had breaks in the process.

Keywords: primary school, modeling, mathematical modeling, crime problem

Procedia PDF Downloads 407

Authors: Zeynep Şahin, Züleyha Yılmaz, Fikret Çankaya

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In today's business world, in which it is difficult to survive, the economic life of products, services or knowledge is considerably reduced. Competitors produce similar products or extra-featured ones instantly. In this environment, the contribution of companies to the social and economic environment is a preferred criterion by consumers alongside products or services. Therefore, consumers need to obtain more detailed information about companies. Besides, this drastic change in the market encourages companies to become sustainable. Sustainable business means the company puts consumed products back. Corporate sustainability, corresponds to sustainability at the level of the company, and gives equal importance to company growth and profitability together with environmental and social issues. The BIST Sustainability Index started to be calculated by the Istanbul Stock Exchange (BIST) in 2014 to evaluate the sustainability performance of companies in Turkey. The main objective of this study is to present the importance of sustainability reports in Turkey. To this aim, the performances of 15 companies in the BIST Sustainability Index were compared the periods before and after entering the index. On the other hand, sustainability reporting practices should be encouraged to increase studies on this issue. In this context, to remain on the agenda of the issue is a further objective of this study. To achieve these objectives, the financial data of the companies in the period before and after entering to the BIST Sustainability Index were analyzed using t-test in Statistical Package for the Social Sciences (SPSS) package. The results of the study showed that no significant difference between the performances of the companies in terms of the net profit margin, the return on assets and equity capital in these periods could be found. Therefore, it can be said that insufficient importance is given to sustainability issues in Turkey. The reasons for this situation might be considered as a lack of awareness due to the recent introduction and calculation of the index. It is expected that the awareness of firms and investors about sustainability will increase, and that they will demonstrate the necessary importance to this issue over time.

Keywords: sustainability reporting, sustainability index, firm performance, BIST sustainability index

Procedia PDF Downloads 277

Authors: Ahmet Erdoğan, Şahin Kesici, Mustafa Baloğlu

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Information technologies have lead to changes in the areas of communication, learning, and teaching. Besides offering many opportunities to the learners, these technologies have changed the teaching methods and beliefs of teachers. What the Technological Pedagogical Content Knowledge (TPACK) means to the teachers is considerably important to integrate technology successfully into teaching processes. It is necessary to understand how to plan and apply teacher training programs in order to balance students’ pedagogical and technological knowledge. Because of many inefficient teacher training programs, teachers have difficulties in relating technology, pedagogy and content knowledge each other. While providing an efficient training supported with technology, understanding the three main components (technology, pedagogy and content knowledge) and their relationship are very crucial. The purpose of this study is to determine whether motivational beliefs and self-regulated learning strategies are significant predictors of mathematics teacher candidates' TPACK perceptions. A hundred seventy five Turkish mathematics teachers candidates responded to the Motivated Strategies for Learning Questionnaire (MSLQ) and the Technological Pedagogical And Content Knowledge (TPACK) Scale. Of the group, 129 (73.7%) were women and 46 (26.3%) were men. Participants' ages ranged from 20 to 31 years with a mean of 23.04 years (SD = 2.001). In this study, a multiple linear regression analysis was used. In multiple linear regression analysis, the relationship between the predictor variables, mathematics teacher candidates' motivational beliefs, and self-regulated learning strategies, and the dependent variable, TPACK perceptions, were tested. It was determined that self-efficacy for learning and performance and intrinsic goal orientation are significant predictors of mathematics teacher candidates' TPACK perceptions. Additionally, mathematics teacher candidates' critical thinking, metacognitive self-regulation, organisation, time and study environment management, and help-seeking were found to be significant predictors for their TPACK perceptions.

Keywords: candidate mathematics teachers, motivational beliefs, self-regulated learning strategies, technological and pedagogical knowledge, content knowledge

Procedia PDF Downloads 482

Authors: Emine Ebru Demirci, Remzi Şahin

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The purpose of this study is to compare Self Compacting Concrete (SCC) and Conventional Concrete (CC), which are used in beams with dense reinforcement, in terms of their capillary absorption. During the comparison of SCC and CC, the effects of two different factors were also investigated: concrete strength class and curing condition. In the study, both SCC and CC were produced in three different concrete classes (C25, C50 and C70) and the other parameter (i.e curing condition) was determined as two levels: moisture and air curing. Beam dimensions were determined to be 200 x 250 x 3000 mm. Reinforcements of the beams were calculated and placed as 2ø12 for the top and 3ø12 for the bottom. Stirrups with dimension 8 mm were used as lateral rebar and stirrup distances were chosen as 10 cm in the confinement zone and 15 cm at the central zone. In this manner, densification of rebars in lateral cross-sections of beams and handling of SCC in real conditions were aimed. Concrete covers of the rebars were chosen to be equal in all directions as 25 mm. The capillary absorption measurements were performed on core samples taken from the beams. Core samples of ø8x16 cm were taken from the beginning (0-100 cm), middle (100-200 cm) and end (200-300 cm) region of the beams according to the casting direction of SCC. However core samples were taken from lateral surface of the beams. In the study, capillary absorption experiments were performed according to Turkish Standard TS EN 13057. It was observed that, for both curing environments and all strength classes of concrete, SCC’s had lower capillary absorption values than that of CC’s. The capillary absorption values of C25 class of SCC are 11% and 16% lower than that of C25 class of CC for air and moisture conditions, respectively. For C50 class, these decreases were 6% and 18%, while for C70 class, they were 16% and 9%, respectively. It was also detected that, for both SCC and CC, capillary absorption values of samples kept in moisture curing are significantly lower than that of samples stored in air curing. For CC’s; C25, C50 and C70 class moisture-cured samples were found to have 26%, 12% and 31% lower capillary absorption values, respectively, when compared to the air-cured ones. For SCC’s; these values were 30%, 23% and 24%, respectively. Apart from that, it was determined that capillary absorption values for both SCC and CC decrease with increasing strength class of concrete for both curing environments. It was found that, for air cured CC, C50 and C70 class of concretes had 39% and 63% lower capillary absorption values compared to the C25 class of concrete. For the same type of concrete samples cured in the moisture environment, these values were found to be 27% and 66%. It was found that for SCC samples, capillary absorption value of C50 and C70 concretes, which were kept in air curing, were 35% and 65% lower than that of C25, while for moisture-cured samples these values were 29% and 63%, respectively. When standard deviations of the capillary absorption values are compared for core samples obtained from the beginning, middle and end of the CC and SCC beams, it was found that, in all three strength classes of concrete, the variation is much smaller for SCC than CC. This demonstrated that SCC’s had more uniform character than CC’s.

Keywords: self compacting concrete, reinforced concrete beam, capillary absorption, strength class, curing condition

Procedia PDF Downloads 371

Authors: Ebrahim Shayesteh, Nikolaos Styliaras, Alin George Raducu, Ozan Sahin, Daniel Pombo VáZquez, Jonas Funkquist, Sotirios Thanopoulos

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One of the important requirements in many code generation projects is defining some of the model parameters tunable. This helps to update the model parameters without performing the code generation again. This paper studies the concept of embedded code generation by MATLAB/Simulink coder targeting the TwinCAT Simulink system. The generated runtime modules are then tested and deployed to the TwinCAT 3 engineering environment. However, defining the parameters tunable in MATLAB/Simulink code generation targeting TwinCAT is not very straightforward. This paper focuses on this subject and reviews some of the techniques tested here to make the parameters tunable in generated runtime modules. Three techniques are proposed for this purpose, including normal tunable parameters, callback functions, and mask subsystems. Moreover, some test Simulink models are developed and used to evaluate the results of proposed approaches. A brief summary of the study results is presented in the following. First of all, the parameters defined tunable and used in defining the values of other Simulink elements (e.g., gain value of a gain block) could be changed after the code generation and this value updating will affect the values of all elements defined based on the values of the tunable parameter. For instance, if parameter K=1 is defined as a tunable parameter in the code generation process and this parameter is used to gain a gain block in Simulink, the gain value for the gain block is equal to 1 in the gain block TwinCAT environment after the code generation. But, the value of K can be changed to a new value (e.g., K=2) in TwinCAT (without doing any new code generation in MATLAB). Then, the gain value of the gain block will change to 2. Secondly, adding a callback function in the form of “pre-load function,” “post-load function,” “start function,” and will not help to make the parameters tunable without performing a new code generation. This means that any MATLAB files should be run before performing the code generation. The parameters defined/calculated in this file will be used as fixed values in the generated code. Thus, adding these files as callback functions to the Simulink model will not make these parameters flexible since the MATLAB files will not be attached to the generated code. Therefore, to change the parameters defined/calculated in these files, the code generation should be done again. However, adding these files as callback functions forces MATLAB to run them before the code generation, and there is no need to define the parameters mentioned in these files separately. Finally, using a tunable parameter in defining/calculating the values of other parameters through the mask is an efficient method to change the value of the latter parameters after the code generation. For instance, if tunable parameter K is used in calculating the value of two other parameters K1 and K2 and, after the code generation, the value of K is updated in TwinCAT environment, the value of parameters K1 and K2 will also be updated (without any new code generation).

Keywords: code generation, MATLAB, tunable parameters, TwinCAT

Procedia PDF Downloads 228

Authors: Mustafa Sengul, Enes Sahin, Sertac Arslan

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Pumpjets are one of the marine propulsion systems frequently used in underwater vehicles nowadays. The reasons for frequent use of pumpjet as a propulsion system are that it has higher relative efficiency at high speeds, better cavitation, and acoustic performance than its rivals. Pumpjets are composed of rotor, stator, and duct, and there are two different types of pumpjet configurations depending on the desired hydrodynamic characteristic, which are with accelerating and decelerating duct. Pumpjet with an accelerating channel is used at cargo ships where it works at low speeds and high loading conditions. The working principle of this type of pumpjet is to maximize the thrust by reducing the pressure of the fluid through the channel and throwing the fluid out from the channel with high momentum. On the other hand, for decelerating ducted pumpjets, the main consideration is to prevent the occurrence of the cavitation phenomenon by increasing the pressure of the fluid about the rotor region. By postponing the cavitation, acoustic noise naturally falls down, so decelerating ducted systems are used at noise-sensitive vehicle systems where acoustic performance is vital. Therefore, duct design becomes a crucial step during pumpjet design. This study, it is aimed to optimize the duct geometry of a decelerating ducted pumpjet for a highly speed underwater vehicle by using proper optimization tools. The target output of this optimization process is to obtain a duct design that maximizes fluid pressure around the rotor region to prevent from cavitation and minimizes drag force. There are two main optimization techniques that could be utilized for this process which are parameter-based optimization and gradient-based optimization. While parameter-based algorithm offers more major changes in interested geometry, which makes user to get close desired geometry, gradient-based algorithm deals with minor local changes in geometry. In parameter-based optimization, the geometry should be parameterized first. Then, by defining upper and lower limits for these parameters, design space is created. Finally, by proper optimization code and analysis, optimum geometry is obtained from this design space. For this duct optimization study, a commercial codedparameter-based optimization algorithm is used. To parameterize the geometry, duct is represented with b-spline curves and control points. These control points have x and y coordinates limits. By regarding these limits, design space is generated.

Keywords: pumpjet, decelerating duct design, optimization, underwater vehicles, cavitation, drag minimization

Procedia PDF Downloads 209

Authors: Meral Huri, Sedef Şahin

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Post-traumatic stress disorder (PTSD) is characterized by psychiatric symptoms and triggered by a terrifying experience which may immediately effect cognitive, affective, behavioral and social skills of the individual. One of the most common noncutaneous cancer among men is prostate cancer. The incidence of psychological stress is quite common in men with prostate cancer. The aim of the study was to explore the PTSD frequency among prostate cancer and define the relationship between occupational participation, coping skills and level of perceived social support among patients with prostate cancer. Forty patients diagnosed with prostate cancer were included in the study. After dividing the patients into two groups ( study/ control) according to type of tumor, we recorded their characteristics and evaluations differences. We evaluated the demographic information form, Structured Clinical Interview for DSM-IV (SCID- I)- Clinical Version for PTSD, Multidimensional Scale of Perceived Social Support, Styles of Coping Inventory and Canadian Occupational Performance Measure (COPM) before and after 1 month from surgery. The mean age of the study group (n:18) was 65.85.6 years (range: 61-79 years). The mean age of the control group (n: 22) was a little bit higher than the study group with mean age 71.3±6.9 years (range: 60-85 years). There was no statistically significant difference between the groups for age and the other characteristics. According to the results of the study, statistically significant difference was found between the level of PTSD of study and the control group. 22% of study group showed PTSD while 13% of the control group showed PTSD (r: 0.02, p<0.001). The scores of study group and control group showed statistically significant difference in five sub-categories of Styles of Coping Inventory. Patients with prostate cancer showed decreased scores in optimistic, seeking social supports and self-confident approach, while increased scores in helpless and submissive sub-categories than the control group (p<0.001). The scores of Multidimensional Scale of Perceived Social Supports of study group and control group showed statistically significant difference. The total perceived social supports score of the study group was 71.34 ± 0.75 while it was 75.34 ± 0.64 for the control group. Total and the sub-category scores of study group were statistically significant lower than the control group. According to COPM, mean scores of occupational participation of study group for occupational performance were 4.32±2.24 and 7.01±1.52 for the control group, respectively). Mean Satisfaction scores were 3,22±2.31 and 7.45±1.74 for the study and control group, respectively. The patients with prostate cancer and benign prostate hyperplasia (BPH) did not show any statistically difference in activity performance (r:0.87) while patients with prostate cancer showed statistically lower scores than the patients with BPH in activity satisfaction (r:0.02, p<0.001).Psycho-social occupational therapy interventions might help to decrease the prevalence of PTSD by increasing associated factors such as the social support perception, using coping skills and activity participation of patients with prostate cancer.

Keywords: activity performance, occupational therapy, posttraumatic stress disorder, prostate cancer

Procedia PDF Downloads 145

Authors: M. H. Arslan, U. K. Sahin, H. Acikgoz-Tufan, I. Gocek, I. Erdem

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Various exterior factors have perpetual effects on textile materials during wear, use and laundering in everyday life. In accordance with their frequency of use, textile materials are required to be laundered at certain intervals. The medium in which the laundering process takes place have inevitable detrimental physical and chemical effects on textile materials caused by the unique parameters of the process inherently existing. Connatural structures of various textile materials result in many different physical, chemical and mechanical characteristics. Because of their specific structures, these materials have different behaviors against several exterior factors. By modeling the behavior of commercial and test textiles as group-wise against laundering process, it is possible to disclose the relation in between these two groups of materials, which will lead to better understanding of their behaviors in terms of similarities and differences against the washing parameters of the laundering. Thus, the goal of the current research is to examine the behavior of two groups of textile materials as commercial textiles and as test textiles towards the main washing machine parameters during laundering process such as temperature, load quantity, mechanical action and level of water amount by concentrating on shrinkage, pilling, sewing defects, collar abrasion, the other defects other than sewing, whitening and overall properties of textiles. In this study, cotton fabrics were preferred as commercial textiles due to the fact that garments made of cotton are the most demanded products in the market by the textile consumers in daily life. Full factorial experimental set-up was used to design the experimental procedure. All profiles always including all of the commercial and the test textiles were laundered for 20 cycles by commercial home laundering machine to investigate the effects of the chosen parameters. For the laundering process, a modified version of ‘‘IEC 60456 Test Method’’ was utilized. The amount of detergent was altered as 0.5% gram per liter depending on varying load quantity levels. Datacolor 650®, EMPA Photographic Standards for Pilling Test and visual examination were utilized to test and characterize the textiles. Furthermore, in the current study the relation in between commercial and test textiles in terms of their performance was deeply investigated by the help of statistical analysis performed by MINITAB® package program modeling their behavior against the parameters of the laundering process. In the experimental work, the behaviors of both groups of textiles towards washing machine parameters were visually and quantitatively assessed in dry state.

Keywords: behavior against washing machine parameters, performance evaluation of textiles, statistical analysis, commercial and test textiles

Procedia PDF Downloads 362

Authors: Elifsu Sahin

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In the world and in Turkey, approximately 1 in 10 people is 65 years of age or older. The age group of 65 and over is the fastest-growing age group since 1990. This demographic aging trend and demographic transformation have spread over a long period in Western Europe and North America, while in Turkey, they have occurred over a relatively short period. The aging of the population poses many challenges in terms of housing supply, housing satisfaction, and economic access to housing, due to factors such as a decrease in the number of people in households, low incomes, and increased time spent in housing and housing neighborhoods. On the other hand, since 2000, neoliberal economic policies and government policies have led to serious growth in the construction and housing sectors in Turkey. During this process, the housing market in Turkey generally produced housing for high-income groups and foreigners. Housing has become an investment instrument, and rising housing prices and rents have seriously reduced both the affordability of housing and households' chances of living in healthy housing. Housing has become a growing problem for vulnerable groups such as low- and middle-income households, students, refugees, and the elderly. Moreover, in recent years, international migration, pandemics, economic crises, inflation, and the expected Istanbul earthquake have raised housing prices and rent in Turkey as a whole, especially in Istanbul. The aim of the study is to investigate how elderly households that don't own homes deal with the economic accessibility of housing and other affordability-related housing problems in the Istanbul Metropolitan Area today, when housing becomes an investment instrument, the issue of social housing is not on the agenda, and households can be added to the market according to their ability to pay. A complex method was adopted in the research, using a combination of various statistical data and interview findings. Based on household income, in-depth interviews were conducted with 100 elderly households who don't own their own homes and were randomly selected in identified neighborhoods, analyzing the micro-area within the districts in the Istanbul Metropolitan Area, where middle- and low-income households are concentrated. The study found that more than 50% of the net income of elderly households was spent on rent and other housing expenses. Some of the households said that they restrict spending on food, health, and entertainment because of their housing expenses. Among the findings of the study is that households receive financial support from their children or move into their children’s house for economic reasons. Due to the decrease in household income, especially after the loss of a spouse, the single individual moves into their children’s house. Moreover, some of the interviewed households had to change their house and move to a smaller, lower-rent house on the urban periphery for economic reasons after retirement, especially after 2020, despite their unwillingness.

Keywords: affordable housing, elderly households, housing policy, istanbul metropolitan area

Procedia PDF Downloads 36

Authors: Pakize Neslihan Taslı, Alev Cumbul, Gul Merve Yalcın, Fikrettin Sahin

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A key experimental trial in the regeneration of large oral and craniofacial defects is the neogenesis of osseous and ligamentous interfacial structures. Currently, oral regenerative medicine strategies are unpredictable for repair of tooth supporting tissues destroyed as a consequence of trauma, chronic infection or surgical resection. A different approach combining the gel-casting method with Hydroxy Apatite HA-based scaffold and different cell lineages as a hybrid system leads to successively mimic the early stage of tooth development, in vitro. HA is widely accepted as a bioactive material for guided bone and tooth regeneration. In this study, it was reported that, HA porous scaffold preparation, characterization and evaluation of structural and chemical properties. HA is the main factor that exists in tooth and it is in harmony with structural, biological, and mechanical characteristics. Here, this study shows mimicking immature tooth at the late bell stage design and construction of HA scaffolds for cell transplantation of human Adipose Stem Cells (hASCs), human Bone Marrow Stem Cells (hBMSCs) and Gingival Epitelial cells for the formation of human tooth dentin-pulp-enamel complexes in vitro. Scaffold characterization was demonstrated by SEM, FTIR and pore size and density measurements. The biological contraction of dental tissues against each other was demonstrated by mRNA gene expressions, histopatologic observations and protein release profile by ELISA tecnique. The tooth shaped constructs with a pore size ranging from 150 to 300 µm arranged by gathering right amounts of materials provide interconnected macro-porous structure. The newly formed tissue like structures that grow and integrate within the HA designed constructs forming tooth cementum like tissue, pulp and bone structures. These findings are important as they emphasize the potential biological effect of the hybrid scaffold system. In conclusion, this in vitro study clearly demonstrates that designed 3D scaffolds shaped as a immature tooth at the late bell stage were essential to form enamel-dentin-pulp interfaces with an appropriate cell and biodegradable material combination. The biomimetic architecture achieved here is providing a promising platform for dental tissue engineering.

Keywords: tooth regeneration, tissue engineering, adipose stem cells, hydroxyapatite tooth engineering, porous scaffold

Procedia PDF Downloads 234

Authors: U. K. Sahin, N. Erdumlu, C. Saricam, I. Gocek, M. H. Arslan, H. Acikgoz-Tufan, B. Kalav

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Finishing is an important part of fabric processing with which a wide range of features are imparted to greige or colored fabrics for various end-uses. Especially, by the addition or impartation of nano-scaled particles to the fabric structure composite fabrics, a kind of composite materials can be acquired. Composite materials, generally shortened as composites or in other words composition materials, are engineered or naturally occurring materials made from two or more component materials with significantly different physical, mechanical or chemical characteristics remaining separate and distinctive at the macroscopic or microscopic scale within the end product structure. Therefore, the technique finishing which is one of the fundamental methods to be applied on fabrics for obtainment of composite fabrics with many functionalities was used in the current study with the same purpose. However, regardless of the finishing materials applied, the efficient life of finished product on offering desired feature is low, since the durability of finishes on the material is limited. Any increase in durability of these finishes on textiles would enhance the life of use for textiles, which will result in happier users. Therefore, in this study, since higher durability was desired for the finishing materials fixed on the fabrics, nano-scaled hollow structured cyclodextrins were chemically imparted by grafting to the structure of conventional cotton fabrics by the help of finishing technique in order to be fixed permanently. By this way, a processed and functionalized base fabric having potential to be treated in the subsequent processes with many different finishing agents and nanomaterials could be obtained. Henceforth, this fabric can be used as a multi-functional fabric due to the encapturing ability of cyclodextrins to molecules/particles via physical/chemical means. In this study, scoured and rinsed woven bleached plain weave 100% cotton fabrics were utilized because textiles made of cotton are the most demanded textile products in the textile market by the textile consumers in daily life. Cotton fabric samples were immersed in treating baths containing β-cyclodextrin and 1,2,3,4-butanetetracarboxylic acid and to reduce the curing temperature the catalyst sodium hypophosphite monohydrate was used. All impregnated fabric samples were pre-dried. The reaction of grafting was performed in dry state. The treated and cured fabric samples were rinsed with warm distilled water and dried. The samples were dried for 4 h and weighed before and after finishing and rinsing. Stability and durability of β-cyclodextrins on fabric surface against external factors such as washing as well as strength of functionalized fabric in terms of tensile and tear strength were tested. Presence and homogeneity of distribution of β-cyclodextrins on fabric surface were characterized.

Keywords: cotton fabric, cyclodextrine, improved durability, multifunctional composite textile

Procedia PDF Downloads 297

Authors: H. E. Budak, B. Arslan-Ilkiz, N. Cakmakci, I. Gocek, U. K. Sahin, H. Acikgoz-Tufan, M. H. Arslan

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The aim of this study is to design a novel laundry algorithm for colored textiles which have significant decoloring problem. During the experimental work, bleached knitted single jersey fabric made of 100% cotton and dyed with reactive dyestuff was utilized, since according to a conducted survey textiles made of cotton are the most demanded textile products in the textile market by the textile consumers and for coloration of textiles reactive dyestuffs are the ones that are the most commonly used in the textile industry for dyeing cotton-made products. Therefore, the fabric used in this study was selected and purchased in accordance with the survey results. The fabric samples cut out of this fabric were dyed with different dyeing parameters by using Remazol Brilliant Red 3BS dyestuff in Gyrowash machine at laboratory conditions. From the alternative reactive-dyed cotton fabric samples, the ones that have high tendency to color loss were determined and examined. Accordingly, the parameters of the dyeing process used for these fabric samples were evaluated and the dyeing process which was chosen to be used for causing high tendency to color loss for the cotton fabrics was determined in order to reveal the level of improvement in color loss during this study clearly. Afterwards, all of the untreated fabric samples cut out of the fabric purchased were dyed with the dyeing process selected. When dyeing process was completed, an experimental design was created for the laundering process by using Minitab® program considering temperature, time and mechanical action as parameters. All of the washing experiments were performed in domestic washing machine. 16 washing experiments were performed with 8 different experimental conditions and 2 repeats for each condition. After each of the washing experiments, water samples of the main wash of the laundering process were measured with UV spectrophotometer. The values obtained were compared with the calibration curve of the materials used for the dyeing process. The results of the washing experiments were statistically analyzed with Minitab® program. According to the results, the most suitable washing algorithm to be used in terms of the parameters temperature, time and mechanical action for domestic washing machines for minimizing fabric color loss was chosen. The laundry algorithm proposed in this study have the ability of minimalizing the problem of color loss of colored textiles in washing machines by eliminating the negative effects of the parameters of laundering process on color of textiles without compromising the fundamental effects of basic cleaning action being performed properly. Therefore, since fabric color loss is minimized with this washing algorithm, dyestuff residuals will definitely be lower in the grey water released from the laundering process. In addition to this, with this laundry algorithm it is possible to wash and clean other types of textile products with proper cleaning effect and minimized color loss.

Keywords: color loss, laundry algorithm, textiles, domestic washing process

Procedia PDF Downloads 361

Authors: C. Amer, M. Sahin

Abstract:

The design of an optimised horizontal axis 5-meter-long wind turbine rotor blade in according with IEC 61400-2 standard is a research and development project in order to fulfil the requirements of high efficiency of torque from wind production and to optimise the structural components to the lightest and strongest way possible. For this purpose, a research study is presented here by focusing on the structural characteristics of a composite wind turbine blade via finite element modelling and analysis tools. In this work, first, the required data regarding the general geometrical parts are gathered. Then, the airfoil geometries are created at various sections along the span of the blade by using CATIA software to obtain the two surfaces, namely; the suction and the pressure side of the blade in which there is a hat shaped fibre reinforced plastic spar beam, so-called chassis starting at 0.5m from the root of the blade and extends up to 4 m and filled with a foam core. The root part connecting the blade to the main rotor differential metallic hub having twelve hollow threaded studs is then modelled. The materials are assigned as two different types of glass fabrics, polymeric foam core material and the steel-balsa wood combination for the root connection parts. The glass fabrics are applied using hand wet lay-up lamination with epoxy resin as METYX L600E10C-0, is the unidirectional continuous fibres and METYX XL800E10F having a tri-axial architecture with fibres in the 0,+45,-45 degree orientations in a ratio of 2:1:1. Divinycell H45 is used as the polymeric foam. The finite element modelling of the blade is performed via MSC PATRAN software with various meshes created on each structural part considering shell type for all surface geometries, and lumped mass were added to simulate extra adhesive locations. For the static analysis, the boundary conditions are assigned as fixed at the root through aforementioned bolts, where for dynamic analysis both fixed-free and free-free boundary conditions are made. By also taking the mesh independency into account, MSC NASTRAN is used as a solver for both analyses. The static analysis aims the tip deflection of the blade under its own weight and the dynamic analysis comprises normal mode dynamic analysis performed in order to obtain the natural frequencies and corresponding mode shapes focusing the first five in and out-of-plane bending and the torsional modes of the blade. The analyses results of this study are then used as a benchmark prior to modal testing, where the experiments over the produced wind turbine rotor blade has approved the analytical calculations.

Keywords: dynamic analysis, fiber reinforced composites, horizontal axis wind turbine blade, hand-wet layup, modal testing

Procedia PDF Downloads 426

Authors: Merve Uzuner Sahin, Kumru D. Atalay, Berna Dengiz

Abstract:

In today’s competitive market, there are many alternative products that can be used in similar manner and purpose. Therefore, the utility of the product is an important issue for the preferability of the brand. This utility could be measured in terms of its functionality, durability, reliability. These all are affected by the system capabilities. Reliability is an important system design criteria for the manufacturers to be able to have high availability. Availability is the probability that a system (or a component) is operating properly to its function at a specific point in time or a specific period of times. System availability provides valuable input to estimate the production rate for the company to realize the production plan. When considering only the corrective maintenance downtime of the system, mean time between failure (MTBF) and mean time to repair (MTTR) are used to obtain system availability. Also, the MTBF and MTTR values are important measures to improve system performance by adopting suitable maintenance strategies for reliability engineers and practitioners working in a system. Failure and repair time probability distributions of each component in the system should be known for the conventional availability analysis. However, generally, companies do not have statistics or quality control departments to store such a large amount of data. Real events or situations are defined deterministically instead of using stochastic data for the complete description of real systems. A fuzzy set is an alternative theory which is used to analyze the uncertainty and vagueness in real systems. The aim of this study is to present a novel approach to compute system availability using representation of MTBF and MTTR in fuzzy numbers. Based on the experience in the system, it is decided to choose 3 different spread of MTBF and MTTR such as 15%, 20% and 25% to obtain lower and upper limits of the fuzzy numbers. To the best of our knowledge, the proposed method is the first application that is used fuzzy MTBF and fuzzy MTTR for fuzzy system availability estimation. This method is easy to apply in any repairable production system by practitioners working in industry. It is provided that the reliability engineers/managers/practitioners could analyze the system performance in a more consistent and logical manner based on fuzzy availability. This paper presents a real case study of a repairable multi-stage production line in lead-acid battery production factory in Turkey. The following is focusing on the considered wet-charging battery process which has a higher production level than the other types of battery. In this system, system components could exist only in two states, working or failed, and it is assumed that when a component in the system fails, it becomes as good as new after repair. Instead of classical methods, using fuzzy set theory and obtaining intervals for these measures would be very useful for system managers, practitioners to analyze system qualifications to find better results for their working conditions. Thus, much more detailed information about system characteristics is obtained.

Keywords: availability analysis, battery production system, fuzzy sets, triangular fuzzy numbers (TFNs)

Procedia PDF Downloads 225

Authors: Huseyin Apdik, Aysegul Dogan, Selami Demirci, Ezgi Avsar Apdik, Fikrettin Sahin

Abstract:

Mesenchymal stem cells (MSCs) are crucial cell types for bone maintenance and growth along with resident bone progenitor cells providing bone tissue integrity during osteogenesis and skeletal growth. Any deficiency in this regulation would result in vital bone diseases. Of those, osteoporosis, characterized by a reduction in bone mass and mineral density, is a critical skeletal disease for especially elderly people. The commonly used drugs for the osteoporosis treatment are bisphosphonates (BPs). The most prominent role of BPs is to prevent bone resorption arisen from high osteoclast activity. However, administrations of bisphosphonates may also cause bisphosphonate-induced osteonecrosis of the jaw (BIONJ). Up to the present, the researchers have proposed several circumstances for BIONJ. However, effects of long-term and/or high dose usage of BPs on stem cell’s proliferation, survival, differentiation or maintenance capacity have not been evaluated yet. The present study will be held to; figure out BPs’ effects on MSCs in vitro in the aspect of cell proliferation and toxicity, migration, angiogenic activity, lineage specific gene and protein expression levels, mesenchymal stem cell properties and potential signaling pathways affected by BP treatment. Firstly, mesenchymal stem cell characteristics of Dental Pulp Stem Cells (DPSCs) and Periodontal Ligament Stem Cells (PDLSCs) were proved using flow cytometry analysis. Cell viability analysis was completed to determine the cytotoxic effects of BPs (Zoledronate (Zol), Alendronate (Ale) and Risedronate (Ris)) on DPSCs and PDLSCs by the 3-(4,5-di-methyl-thiazol-2-yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium (MTS) assay. Non-toxic concentrations of BPs were determined at 24 h under growth condition, and at 21 days under osteogenic differentiation condition for both cells. The scratch assay was performed to evaluate their migration capacity under the usage of determined of BPs concentrations at 24 h. The results revealed that while the scratch closure is 70% in the control group for DPSCs, it was 57%, 66% and 66% in Zol, Ale and Ris groups, respectively. For PDLSs, while wound closure is 71% in control group, it was 65%, 66% and 66% in Zol, Ale and Ris groups, respectively. As future experiments, tube formation assay and aortic ring assay will be done to determinate angiogenesis abilities of DPSCs and PDLSCs treated with BPs. Expression levels of osteogenic differentiation marker genes involved in bone development will be determined using real time-polymerase change reaction (RT-PCR) assay and expression profiles of important proteins involved in osteogenesis will be evaluated using western blotting assay for osteogenically differentiated MSCs treated with or without BPs. In addition to these, von Kossa staining will be performed to measure calcium mineralization status of MSCs.

Keywords: bisphosphonates, bisphosphonate-induced osteonecrosis of the jaw, mesenchymal stem cells, osteogenesis

Procedia PDF Downloads 263