Yazar "Tanrikulu, Mahmud Yusuf" seçeneğine göre listele

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    Atomic layer deposition synthesized TiOx thin films and their application as microbolometer active materials
    (A V S Amer Inst Physics, 2016) Tanrikulu, Mahmud Yusuf; Rasouli, Hamid Reza; Ghaffari, Mohammad; Topalli, Kagan; Okyay, Ali Kemal
    This paper demonstrates the possible usage of TiOx thin films synthesized by atomic layer deposition as a microbolometer active material. Thin film electrical resistance is investigated as a function of thermal annealing. It is found that the temperature coefficient of resistance values can be controlled by coating/annealing processes, and the value as high as -9%/K near room temperature is obtained. The noise properties of TiOx films are characterized. It is shown that TiOx films grown by atomic layer deposition technique could have a significant potential to be used as a new active material for microbolometer-based applications. (C) 2016 American Vacuum Society.
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    Digitally alloyed ZnO and TiO2 thin film thermistors by atomic layer deposition for uncooled microbolometer applications
    (A V S Amer Inst Physics, 2017) Tilkioglu, Bilge T.; Bolat, Sami; Tanrikulu, Mahmud Yusuf; Okyay, Ali Kemal
    The authors demonstrate the digital alloying of ZnO and TiO2 via atomic layer deposition method to be utilized as the active material of uncooled microbolometers. Depositions are carried out at 200 degrees C. Crystallinity of the material is shown to be degraded with the increase of the Ti content in the grown film. A maximum temperature coefficient of resistance (TCR) of 5.96%/K is obtained with the films containing 12.2 at. % Ti, and the obtained TCR value is shown to be temperature insensitive in the 15-22 degrees C, thereby allowing a wide range of operation temperatures for the low cost microbolometers. (C) 2017 American Vacuum Society.
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    LWIR all-atomic layer deposition ZnO bilayer microbolometer for thermal imaging
    (Spie-Soc Photo-Optical Instrumentation Engineers, 2017) Poyraz, Muhammet; Gorgulu, Kazim; Sisman, Zulkarneyn; Tanrikulu, Mahmud Yusuf; Okyay, Ali Kemal
    We propose an all-ZnO bilayer microbolometer, operating in the long-wave infrared regime that can be implemented by consecutive atomic layer deposition growth steps. Bilayer design of the bolometer provides very high absorption coefficients compared to the same thickness of a single ZnO layer. High absorptivity of the bilayer structure enables higher performance (lower noise equivalent temperature difference and time constant values) compared to single-layer structure. We observe these results computationally by conducting both optical and thermal simulations. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
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    Priority and age specific vaccination algorithm for the pandemic diseases: a comprehensive parametric prediction model
    (Bmc, 2022) Tutsoy, Önder; Tanrikulu, Mahmud Yusuf
    Background There have been several destructive pandemic diseases in the human history. Since these pandemic diseases spread through human-to-human infection, a number of non-pharmacological policies has been enforced until an effective vaccine has been developed. In addition, even though a vaccine has been developed, due to the challenges in the production and distribution of the vaccine, the authorities have to optimize the vaccination policies based on the priorities. Considering all these facts, a comprehensive but simple parametric model enriched with the pharmacological and non-pharmacological policies has been proposed in this study to analyse and predict the future pandemic casualties. Method This paper develops a priority and age specific vaccination policy and modifies the non-pharmacological policies including the curfews, lockdowns, and restrictions. These policies are incorporated with the susceptible, suspicious, infected, hospitalized, intensive care, intubated, recovered, and death sub-models. The resulting model is parameterizable by the available data where a recursive least squares algorithm with the inequality constraints optimizes the unknown parameters. The inequality constraints ensure that the structural requirements are satisfied and the parameter weights are distributed proportionally. Results The results exhibit a distinctive third peak in the casualties occurring in 40 days and confirm that the intensive care, intubated, and death casualties converge to zero faster than the susceptible, suspicious, and infected casualties with the priority and age specific vaccination policy. The model also estimates that removing the curfews on the weekends and holidays cause more casualties than lifting the restrictions on the people with the chronic diseases and age over 65. Conclusion Sophisticated parametric models equipped with the pharmacological and non-pharmacological policies can predict the future pandemic casualties for various cases.
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    The evolution of nanoscale pores with post-annealing and the structure-electrical property correlation in vanadium oxide thin films
    (Elsevier Science Sa, 2022) Dirican, Emrah; Yagci, Ahmet Murat; Tanrikulu, Mahmud Yusuf; Okszoglu, Ramis Mustafa
    Structure-property correlation in vanadium oxide nanoscale thin films used in uncooled thermal detectors is a crucial question for device performance. The purpose of this work is to investigate the evolution of the nanoscale pores with post-annealing temperature and its correlation to electrical properties. It is observed that the as-deposited film has an amorphous matrix containing nanoscale crystal grains of VO2, V2O5, and V6O13 phases, and additionally nanoscale fibrous-like pores. The film post-annealed at 200 C under high purity N-2 atmosphere for 3 h possesses nanoscale crystal grains predominantly with the VO2 phase besides V6O13 and nanoscale spherical pores. After post-annealing at 300 ?, a clear enhancement in crystallinity and diminishing of amorphous structure has been found, and the film contains VO2, V2O3, and V(6)O(13 )phases, additionally larger pores and cracks. The electrical resistance and temperature coefficient of resistance increase with increasing temperature, whereas the electrical noise reduces after annealing at 200 ?& nbsp;and increases again at 300 ?. The best combination of values for 1/f noise corner frequency (5.7 kHz), electrical resistance (90 k omega), and temperature coefficient of resistance (-2.71 %K- 1) is obtained for the film after post-annealing at 200 ?, favorable for application.