470 research outputs found
Solid‐phase microextraction and ion chromatographic analysis of anions based on polypyrrole electrode
No full textWOS: 000255043100067The polypyrrole (PPy) film was used for the selective extraction of trace levels of chloride, nitrite, and nitrate ions by solid phase micro-extraction (SPME). PPy film was electrochemically prepared from aqueous solutions of pyrrole and LiClO4 under N-2 atmosphere at constant potential of +0.80 V (versus Ag/AgCl). The anion uptake and release properties of the PPy film electrodes were examined under both open circuit and controlled potential conditions for prospective applications in electrochemically controlled solid-phase microextraction (EC-SPME). Applied positive and negative potentials facilitated the extraction and desorption of anions, respectively. Ions were desorbed into sample aliquot and were determined by ion chromatography (IC). The effect of uptake/release parameters, potential, time, pH of the uptake solution, on EC-SPME of anions was investigated. The method was validated using a standard reference material and tested for the determination of the ions in water sample
In situ electrochemical solid-phase extraction of anions and cations using polypyrrole and overoxidized sulfonated polypyrrole
No full textWOS: 000255270700007PubMed ID: 18371893A new method for the extraction of both anions and cations is proposed using electro-synthesized polypyrrole (PPy) and overoxidized sulfonated polypyrrole film (OSPPy). In situ anion (chloride, nitrate, sulfate) and cation (calcium, magnesium) uptake and release were examined under controlled potential conditions for prospective applications in electrochemically controlled solid-phase extraction (EC-SPE). The PPy film was used as an anode (anion-exchanger) and OSPPy film was used as a cathode (cation-exchanger) material and reverse order of the electrodes were investigated in EGSPE. This new cell arrangement containing two ion exchanger polymer electrodes was developed to provide in situ removal of both anions and cations from aqueous solution. Simple preparation of the film coatings on a platinum plate was possible using a constant potential method. Applied positive and negative potentials facilitated the in situ extraction and desorption of ions, respectively. Both anions and cations were desorbed into sample aliquot and were determined by ion chromatography (IC). The method was validated using a standard reference material and tested for the determination of the ions in real water sample
Simulation based optimization for world line card production system
No full textApak, Sinan (Arel Author), Ercan, Sami (Arel Author)Simulation based decision support system is one of the most commonly used tools to examine complex production systems. The simulation approach provides process modules which can be adjusted with certain parameters by using data relatively easily obtainable in production process. World Line Card production system simulation is developed to evaluate the optimality of existing production line via using discrete event simulation model with variety of alternative proposals. The current production system is analysed by a simulation model emphasizing the bottlenecks and the poorly utilized production line. Our analysis identified some improvements and efficient solutions for the existing system
Modal properties of parallel plate waveguide partially loaded with double negative materials
No full textPekmezci, Ayşegül (Dogus Author) -- Topuz, Ercan (Dogus Author)Properties of eigen-solutions in parallel plate waveguides partially loaded with Lorentz type Double Negative Materials (DNG), modelled by lossless/lossy, identical/non-identical electric, magnetic parameters are presented. Modal cut-off phenomena associated with surface waves, transitions between evanescent/propagating, forward/backward waves and their dependence on frequency, filling factor and dispersive material parameters are investigated. Novel conditions are given for the existence of surface waves and for the emergence of complex eigenvalues in the absence of losses, and supported with numerical results of exact frequency domain analysis
Finite difference time domain formulation for epsilon-negative medium using wave equation
No full textPekmezci, Ayşegül (Dogus Author) -- Topuz, Ercan (Dogus Author)A novel approach utilizing one-dimensional (1D) wave equation based finite difference time domain (FDTD) formulations for Lorentz-type Epsilon-Negative (ENG) medium is developed. To demonstrate the validity and accuracy of the formulation, reflection of a plane wave normally incident at free spaceENG interface is compared with the analytical solution. Moreover, propagation characteristics of Lorentz-type ENG medium is investigated using the FDTD formulations both for wave equation and Maxwell's curl equations in 1D case. Comparisons of memory and computational time requirements of both formulations are given
Film Festivalleri 3
No full textBu çalışma Prof. Dr. Mutlu Binark’ın yürütücülüğünü üstlendiği, Arş. Gör. ToygarErcan’ın araştırmacı olarak görev aldığı 20488 ID numaralı Hacettepe ÜniversitesiBilimsel Araştırma Projeleri Tez Projeleri tarafından desteklenmiştir.özTürkiye’de ilk uzun metrajlı kurgu filmini çeken ya da çekecekolan yönetmen adaylarının adaylıktan mezun olarak “yönetmenlik”konumuna adım attıkları alan film festivalleridir. Yönetmen adaylarıKültür ve Turizm Bakanlığı Sinema Genel Müdürlüğü tarafındanverilen “İlk Uzun Metrajlı Kurgu Film Yapım Desteği” kategorisinebaşvurmaya hazırlandıklarından itibaren bir “rüşt ispatlama” çabasıve sürecine girerler. Bu süreç onların daha deneyimli yönetmenlerdenfarklı bir bağımlılık ilişkisi ile karşılaşmalarına yol açar. Sinemaendüstrisinde kalıcılıkları ile doğrudan bağlantılı olan bu bağımlılıkilişkisi öncelikle söz konusu “İlk Uzun Metrajlı Kurgu Film YapımDesteği” ile, sonrasında ise film festivalleri ile kurulur ve daha deneyimliyönetmenlere göre yönetmen adayları hem bakanlık desteklerinehem de film festivallerine endüstride var olabilmek için dahabağımlı konumdadır.</p
Showrooming ve Webrooming’i Kullanarak Ürün Ve Hizmet Talep Eden Tüketicilerin Satın Alma Davranışlarının Karşılaştırılması: İskenderun Teknik Üniversitesi Öğrencileri Üzerine Bir Uygulama
No full textAlternatif markaların yoğun olduğu günümüz dünyasında her tüketicinin istek ve ihtiyaçları doğrultusunda tercih edeceği markalar oldukça fazladır. Bu sebeple istek ve ihtiyaçlarını çok hızlı bir şekilde karşılamak isteyen her tüketici, ya ürün ve hizmetleri satın almak için fiziksel mağazayı ziyaret etmekte ve sonrasında çevrimiçi mağazalardan satın alım işlemini web siteleri üzerinden gerçekleştirmekte (showrooming); ya da çevrimiçi mağazaları ziyaret ederek sonrasında fiziksel mağazalardan alışveriş işlemini gerçekleştirmektedir (webrooming). Bu sebeple işletmeler, her iki (showrooming, webrooming) durumu da dikkate alarak stratejiler geliştirmekte ve tüketicilerin satın alma davranışlarına göre rekabet avantajı sağlayacak politikalar belirlemek için çok yoğun çaba sarf etmektedirler. Bu çalışmanın amacı, showrooming ve webrooming yolunu tercih ederek ürün veya hizmet satın alan tüketicilerin nasıl bir davranış farklılığı gösterdiğini tespit etmek üzerine olmuştur. Bu amaçtan yola çıkarak İskenderun Teknik Üniversitesinde okuyan 400 öğrenci ile yüz yüze görüşülerek anket yöntemi ile veriler toplanmış ve elde edilen veriler SPSS 23.0 paket programından faydalanılarak bağımsız örneklem T testine göre, tek yönlü varyans analizine (ANOVA) göre ve regresyon analizine göre test edilmiştir.[No abstract available
First and second order mur type ABCs for DNG media
No full textPekmezci, Ayşegül (Dogus Author) -- Topuz, Ercan (Dogus Author)Reflections from boundaries of the FDTD computational domain lead to inaccurate, even unstable codes when dealing with problems involving double negative (DNG) materials. Here, an efficient and simple algorithm is presented for terminating FDTD in DNG medium which is based on first and second order Mur’s absorbing boundary conditions (ABC). FDTD update equations for Mur’s ABC formulations are obtained from frequency domain one-way wave equations using piecewise linear recursive convolution (PLRC) method. Numerical examples are given both for 1D and 2D scenarios to demonstrate the validity and stability of the proposed Mur formulations, and its advantages over uniaxial perfectly matched layer (UPML) in reducing computational time and memory requirements
An examination of the relationship between teaching profession ethics and self-efficacy
No full textBu araştırmada; öğretmenlerin meslek etiği algıları ile özyeterlilik algıları arasındaki ilişki ve öğretmenlerin özyeterlilikleri "yaş, cinsiyet, medeni durum, statü (öğretmen, eğitim yöneticisi), mesleğini isteyerek seçme durumu, doğum yerinde çalışma durumu, sendika üyesi olma durumu" değişkenleri açısından incelendi. Araştırma nicel verilere dayalı ilişkisel tarama modelinde bir araştırmadır. Araştırmanın çalışma evreni Konya ve Karatay ilçesinde faaliyet gösteren 30 okul ve bu okullarda görev yapan 928 öğretmen, 82 eğitim yöneticisi olarak belirlenmiştir. Araştırmada örneklem, araştırma evreninden tesadüfi küme örnekleme alma yöntemiyle seçilmiştir. Araştırma çalışma grubu seçtiğimiz okullarda görev yapan 272 öğretmen ve 72 eğitim yöneticisinden oluşmaktadır. Araştırmada "Öğretmen Özyeterlik Ölçeği" ile "Öğretmen Etik Davranışlar Ölçeği" kullanılmıştır. Araştırma genelinde öğretmenlerin ve eğitim yöneticilerinin meslek etiği ve özyeterlik algıları arasında anlamlı bir ilişki bulunmuştur. Meslek etiği algı düzeyleri, özyeterlik algı düzeyleri üzerindeki etkisi pozitif ve istatistiksel olarak anlamlıdır. Bazı demografik değişkenlerde öğretmen özyeterliliği alt boyut puan ortalamaları anlamlı bir farklılık gösterirken, bazılarında anlamlı bir farklılık göstermemektedir.In this study; The relationship between teachers' perceptions of professional ethics and self-efficacy perceptions were examined in terms of variables such as age, gender, marital status, status (teacher, education manager), voluntary selection status, working status at birth place, status of union membership. The research is a research on relational screening model based on quantitative data. The study universe consists of 30 schools in Konya and Karatay, 928 teachers working in these schools, 82 education administrators. Sampling in the study was selected by random sampling from the research universe. The research study group consists of 272 teachers and 72 education administrators who work in selected schools. "Teacher Self-Efficacy Scale" and "Teacher Ethics Behavior Scale" were used in the study. There was a significant relationship between profession ethics and self-efficacy perceptions of teachers and education administrators. Vocational ethical perception levels and self-efficacy perceptions were positively and statistically significant. In some demographic variables, teacher self-efficacy subscale scores showed a meaningful difference, while some did not show any significant difference
Monitoring system for investigating the effect of temperature change on optical properties
No full textKara, Ercan (Dogus Author)Knowledge about the changes in optical properties is needed for planning safer and more accurate laser treatments. A monitoring system was developed to study how the optical properties of a lipid emulsion are affected by temperature changes. A double-integrating-sphere system is modified with a controlled heating apparatus to measure the temperature-dependent diffuse reflectance and total transmittance values. The absorption and reduced scattering coefficients were estimated from the reflectance and transmittance values using an inverse adding-doubling method. The total transmittance showed positive correlation with temperature while the diffuse reflectance was found to be negatively correlated. Although the absorption coefficient did not demonstrate a statistically significant change with temperature, the reduced scattering coefficient was negatively correlated. By using the obtained optical properties, Monte Carlo simulations were performed to observe the difference in light propagation within a tissue. The results indicate that temperature-dependent changes in optical properties should be taken into consideration for a safer laser treatment
- …
