483 research outputs found
Design and simulation of a novel fungus-shaped center embossed diaphragm for fiber optic pressure sensors
No full textA novel structure with a fungus-shaped center embossed diaphragm (FCED) geometry has been proposed to modify in diaphragm-based Fabry-Perot fiber optic pressure sensors (FP-FOPS). The proposed FCED geometry was obtained by adding a pillar between the mesa and diaphragm. Before the simulation analysis of FCED, we derived mathematical equations of attenuation factor widening the acceptance radius. The attenuation factor is defined to understand sensor loss, which is neglected in the literature. With this derived formula, the light reflected from the deflected diaphragm and the light unguided in the fiber was detected. Since the deformation angle is zeroized in the FCED structures, the sensor loss due to the attenuation factor is eliminated. All the incident light being re-guided in the fiber. With FCED design's help, the decreasing sensitivity in the center embossed diaphragms (CED) has been prevented. Moreover, the deviation of the frequency response of FCED remains lower than 1% compared with the results of conventional diaphragms. As a result, it produces a more stable sensor, and the FCED structure is less affected by manufacturing errors. The researchers can benefit from the use of our presented results when designing and producing new diaphragm-based FP-FOPS
Design and optimization of a single-mode rib waveguide using lithium niobate
No full textIn photonic integrated circuits (PICs), singlemode waveguides play a critical role in ensuring low-loss and stable light transmission. Owing to its remarkable electro-optic, piezoelectric, and nonlinear optical properties, lithium niobate (LiNbO _{3 , LN) has emerged as a prominent material for integrated photonic systems. Recently, the development of the lithium niobate on insulator (LNOI) platform has enabled LN to achieve high refractive index contrast and compatibility with silicon-based fabrication processes. In this study, geometric parameter optimization was carried out to achieve single-mode operation in a rib waveguide. The optimization process utilized the particle swarm optimization (PSO) algorithm, where the width and height of the waveguide was analyzed based on the effective refractive index (\boldsymbol{n _{\text {eff ) obtained via the Eigenmode Solver in Lumerical MODE. The results indicate that this approach not only ensures single-mode propagation but also enhances light confinement and guiding efficiency. Consequently, this work presents a systematic method for designing high-performance rib waveguides for LNOI-based electro-optic modulators and other photonic components
Forward and Reverse Bias Current-Voltage Characteristics of Au/N-si Schottky Barrier Diodes With and Without Sno<sub>2</Sub> Insulator Layer
No full textAydemir, Umut/0000-0001-5396-4610; Aydemir, Umut/0000-0001-5396-4610; Gökçen, Muharrem/0000-0001-9063-3028The effects of interfacial insulator layer, interface states (N-ss) and series resistance (R-s) on the electrical characteristics of Au/n-Si structures have been investigated using forward and reverse bias current-voltage (I-V) characteristics at room temperature. Therefore, Au/n-Si Schottky barrier diodes (SBDs) were fabricated as SBDs with and without insulator SnO2 layer to explain the effect of insulator layer on main electrical parameters. The values of ideality factor (n), R-s and barrier height (Phi(Bo)) were calculated from ln(I) vs. V plots and Cheung methods. The energy density distribution profile of the interface states was obtained from the forward bias I-V data by taking bias dependence of ideality factor, effective barrier height (Phi(e)) and R-s into account for MS and MIS SBDs. It was found that N-ss values increase from at about mid-gap energy of Si to bottom of conductance band edge of both SBDs and the MIS SBD's N-ss values are 5-10 times lower than those of MS SBD's. An apparent exponential increase from the mid-gap towards the bottom of conductance band is observed for both SBDs' (MS and MIS) interface states obtained without taking R-s into account. (C) 2011 Elsevier B.V. All rights reserved.Duzce University [2010.05.02.056]This work is supported by Duzce University Scientific Research Project (Project no. 2010.05.02.056)
Use of 2D In 2 Se 3 single crystal as a diaphragm material for fabry-perot fiber optic acoustic sensors
No full textThe diaphragm-based sensor tip, which has a critical design in Fabry-Perot fiber optic acoustic sensor production, directly affects device performance. Fabry-Perot fiber optic acoustic sensors tip designs and investigations on different geometric dimensions and different diaphragm materials continue in the literature. In this study, it is predicted that graphene-like two-dimensional In2Se3 single crystal can be used for the diaphragm material which we report for the first time in the literature. Analytical calculations and numerical simulations have been carried out in order to use two-dimensional In2Se3 single crystals as diaphragm material for Fabry-Perot fiber optic acoustic sensors tip production. The calculation results of the Fabry-Perot fiber optic acoustic sensors tip we designed using In2Se3 single crystal are compared with conventional sensor tip made from Si, SiO2 and graphene as a diaphragm in the literature. Since In2Se3 crystal has a high refraction index, sensor visibility allows for long Fabry-Perot cavities, which creates alternative solutions where very short Fabry-Perot cavities are not possible. Another advantage of this feature is that the inner surface of the diaphragm does not need to be coated with reflective materials like gold, silver etc. Using the high density of In2Se3 crystals for diaphragm materials results in reducing the percentage of frequency in transitions from less dense to more dense environments. According to the simulation results, it is seen that it has high sensitivity of 64.12 nm/kPa and this is the result of having a low Young's modulus than other diaphragm materials like Si, SiO2, graphene of the same geometry reported in the literature. The calculation results were also obtained for other materials as 26.54 nm/kPa, 62.58 nm/kPa, and 4.57 nm/kPa for Si, SiO2 and graphene, respectively. The innovative diaphragm design proposed in this work for Fabry-Perot fiber optic acoustic sensors tip production has been advised alternative solutions when sensor sensitivity and visibility must be considered.Erciyes Üniversitesi - FDK-2016-6811 - FDK-2016-681
Advances in Software Engineering and Aeronautics
No full textAvionics, like any other safety-critical real-time systems, pose unique challenges on system design, development, and testing. Specifically, the rigorous certification process mandated for avionics software calls for additional attention. The DO-178C Software Considerations in Airborne Systems and Equipment Certification provides detailed guidelines to ensure safety measures. This chapter gives a different angle to avionics development and certification, highlighting model-based approaches for advancing the design, development, testing, and maintenance of airborne software systems. Modern software engineering processes such as agile and scrum are discussed as the new techniques in speeding up the certification hurdle, while achieving higher return on investment
A Thematic Review of the Present Photonic Education
No full textIn the presented study, we discussed the thematic review of 68 recent conference studies focused on elementary and secondary school levels to enlighten the future needs of Optics and Photonics Education
DODEKAHİDRO-KLOSO-DODEKABORAT YÜKLÜ POLİMER MİSELLER İÇEREN ÇOK KATMANLI KAPSÜLLERİN HAZIRLANMASI
No full textBoron Neutron Capture Therapy (BNCT) is a non-invasive radiotherapy technique which is based on delivery of non-radioactive 10B compounds to cancer cells and irradiation of the tumour tissues with low energy thermal neutrons. It is a promising radiotherapy technique due to reduce the side effects of the treatment.
The main goal of this thesis is to prepare a non-toxic polymer vehicle to provide efficient delivery of 10B to cancer cells. Dodecahydro-closo-dodecaborate (B12H12)2- (B12) anion was utilized as a model 10B containing agent because of its high boron concentration. Quaternized poly(2-vinyl pyridine)-b-poly(ethylene oxide) (QP2VP-b-PEO) was chosen as a model neutral-cationic block copolymer to construct the carrier. The electrostatic association between QP2VP and B12 induced self-assembly of QP2VP-b-PEO, resulting in micelles with (B12+QP2VP)-core and PEO-corona. (B12+QP2VP)-b-PEO micelles were found to be not stable against dilution in biological medium.
Layer-by-Layer (LbL) deposition technique was used to self-assemble these micelles onto colloidal CaCO3 microparticles to enhance their stability. Tannic acid (TA) was used to drive the LbL assembly through hydrogen bonding interactions between hydrogen accepting PEO-corona and hydrogen donating TA. Stability of LbL capsules in biological medium was assured by construction of barrier layers composed of poly(N-vinyl-caprolactam) (PVCL) and TA on top of (B12+QP2VP)-b-PEO micelles and TA multilayers.
Cytotoxicity and cellular association of LbL capsules was assessed in non-hollow and hollow form using Hep G2 cell line. Capsules were found to show no systematic cytotoxicity on Hep G2 cell line.
Cellular association studies and boron concentrations determined through inductively coupled plasma optical emission spectroscopy (ICP-OES) showed that both non-hollow and hollow capsules associated with Hep G2 cells and delivered boron to the cells.
Overall, this study generated fundamental knowledge on B12 induced micellization and stabilization of micelles in biological medium. These findings may form a basis to develop polymer carriers for boron delivery for BNCT.Bor Nötron Yakalama Terapisi (BNCT), radyoaktif olmayan 10B bileşiklerinin kanser hücrelerine taşınması sonrasında tümör dokularının düşük enerjili termal nötronlarla ışınlanmasına dayanan ve invazif olmayan bir radyoterapi tekniğidir. Tedavinin yan etkisinin az olması nedeniyle bu teknik umut vadeden bir radyoterapi biçimidir.
Bu tezin temel amacı, 10B'nin kanser hücrelerine verimli bir şekilde taşınmasını sağlamak için toksik olmayan bir polimer taşıyıcı geliştirmektir. Dodekahidro-kloso-dodekaborat (B12H12)2- (B12) anyonu yüksek bor içeriğinden dolayı 10B içeren model ajan olarak kullanılmıştır. Kuaternize poli(2-vinil piridin)-b-poli(etilen oksit) (QP2VP-b-PEO) ise, taşıyıcıyı oluşturmak için model bir nötr-katyonik blok kopolimer olarak seçilmiştir. QP2VP ve B12 arasındaki elektrostatik etkileşim, QP2VP-b-PEO'nun kendi kendine yapılanmasını sağlamış, (B12+QP2VP)-çekirdek ve PEO-korona yapısına sahip misellerin oluşmasını tetiklemiştir. Fakat (B12+QP2VP)-b-PEO misellerinin biyolojik ortamda seyrelmeye karşı kararlı olmadığı tespit edilmiştir.
(B12+QP2VP)-b-PEO misellerinin kararlılıklarını artırmak için katman-katman biriktirme (LbL) yöntemi ile kolloidal CaCO3 mikroparçacıklar üzerine (B12+QP2VP)-b-PEO miselleri kendiliğinden yapılandırılmıştır. Katman-katman yapılanma, TA kullanılarak hidrojen kabul edici PEO-kabuk ve hidrojen verici TA arasında kurulan hidrojen bağları etkileşimi sayesinde gerçekleştirilmiştir. LbL kapsüllerin biyolojik ortamdaki kararlılığı, (B12+QP2VP)-b-PEO miseller ve TA çok-katmanlı kapsüllerinin üzerinde biriktirilen poli(N-vinil-kaprolaktam) (PVCL) ve TA’dan oluşan bariyer tabaka ile sağlanmıştır.
LbL kapsüllerin sitotoksisitesi ve hücre ile etkileşimleri, Hep G2 hücre hattı kullanılarak içi boş olmayan ve içi boş kapsüller ile takip edilmiştir. Kapsüllerin, Hep G2 hücre hattı üzerinde majör sistematik sitotoksisite göstermediği tespit edilmiştir.
Hücre ile etkileşim çalışmaları ve indüktif eşleşmiş plazma optik emisyon spektroskopisi (ICP-OES) yöntemiyle belirlenen bor derişimi analizleri, içi boş olmayan ve içi boş kapsüllerin hücrelerle etkileştiğini ve hücrelere bor taşınabildiğini göstermiştir.
Genel olarak, bu çalışma B12 ile tetiklenmiş miselizasyon ve misellerin biyolojik ortamlardaki kararlılığı hakkında temel bilgi üretilmesini sağlamıştır. Bulgular, BNCT’e yönelik bor taşınımı yapacak polimer taşıyıcılar geliştirmek için bir temel oluşturabilecek niteliktedir.M.S. - Master of Scienc
Participatory policy-making, participatory civil society: A key for dissolving elite rule in new democracies in the era of globalization
Get PDFKorkut, Umut (Dogus Author)The author argues that in democracies a strong state and strong civil society are not mutually exclusive. Only a democratic, legitimate, and strong state can provide the environment for civil society activities to flourish; in return, only a strong and a participatory civil society can outline the reach of state strength vis-`a-vis the society. The author discusses the need for civil society organizations to collaborate with policy-making institutions, in which they can negotiate policy concerns with ministers and officials while retaining an independent distance from the state and the political parties. Further, the author argues that an environment as such would provide for the transformative capacity of human agency to manifest itself in full in a globalizing world. The author discusses how participatory state and çivil society structures will enhance the role of the human agency in order to dissolve elite rule, especially in new democracies
: An Inquiry into a Non-Dualistic Duality of Human and Nonhuman
No full textIn-Habitant is an art and life project based on artist Umut Tasa’s decade-long encounters with urban wildlife. It is a quest to utilize art as a research method to contemplate her memories, nature discoveries, audiovisual records, and archive of haiku and prose through a body of artworks. These artworks bring together the corporeality of nonhumans with their digital re-presentation and literary text with creative coding. The author inquires into dualistic and nondualistic ontological approaches to human-nonhuman relations in urban settings
The enhanced lifetime of printed GaS-based photodetectors with polymer encapsulation
No full textExhibiting excellent absorption in the UV-visible wavelength range makes layered gallium sulfide (GaS) semiconductor material a promising candidate for use in electronics and optoelectronics applications. Recently, a fully printed GaS-based photodetector has been proposed and fabricated, rendering a low-cost fabrication process in flexible electronics. However, the degradation of the semiconductor layer due to environmental conditions causes reliability issues and shortens their lifetime. Thus, in this study, an attempt has been made to encapsulate printed GaS-based photodetector using different polymers to hinder the degradation. It is demonstrated that encapsulating the printed GaS-based photodetector by utilizing the polymer-capping method with styrene copolymers, Polystyrene-block-polyisoprene-block-polystyrene, highly hydrogenated poly(styrene)-block-poly (butadiene), partially hydrogenated poly(styrene)-block-poly(butadiene), increases the performance of the photodetector. The efficiency of the GaS-based photodetector printed on flexible polyethylene terephthalate (PET) substrate has reached up to 123 % in responsivity in 6 weeks after the polymer coating. Also, the device figure of merit, the detectivity value of the printed photodetector, has increased more than three times after the polymer coating compared to its as-deposited state. Meanwhile, it is observed that the fall and rise times of the printed GaS photodetector have remained constant. Based on these results attained in this study, it can be claimed that the polymer coating provides high performance and long stability in the printed GaS-based photodetectors on flexible substrates, which will pave the way for the further implementations of III-VI group layered semiconductor materials in electronics and optoelectronics applications
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