Browsing by Author "Bilsel, Mustafa"

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    A Concatenated Up And Down Tapered Fıber For Sımultaneous Measurement Of Straın And Temperature
    (Ankara Üniversitesi Fen Fakültesi, 2020-07-01) Bilsel, Mustafa; Navruz, İsa; Elektrik-Elektronik Mühendisliği; Mühendislik Fakültesi
    A novel fiber optical sensor based on in-line fiber Mach-Zehnder interferometer for simultaneous measurement of strain and temperature is proposed and demonstrated experimentally. The interferometer is simple, extremely robust and highly sensitive and consists of two concatenated parts; one is a down-tapered fiber (DTF) and the other is an up-tapered fiber (UTF). UTF and DTF sections of the sensor are fabricated by using a commercial fiber splicer and a non-commercial setup based on heating and stretching a portion of a standard single-mode fiber, respectively. While UTF section behaves as a beam splitter to decompose the injected light into core and cladding modes, DTF section provides evanescent field to access the surrounding environment. Experimental results indicate that the resolutions of 0.83 °C and 45.80 micro-epsilon were achieved in temperature and strain, respectively, for simultaneous measurement with a 10 pm of wavelength resolution.
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    Çok amaçlı ölçümler için inceltme tekniği kullanan tek damarlı fiber sensörlerin geometrik tasarımı
    (Fen Bilimleri Enstitüsü, 2021) Bilsel, Mustafa; Navruz, İsa; Elektrik-Elektronik Mühendisliği
    Optical fibers that can carry information by light have undoubtedly made the greatest contribution to the development of modern communication technologies. Optical fibers, which offer advantages such as very high communication bandwidth, low power loss, small size and safety against signal external factors, attract much attention not only in the telecommunication sector but also in different disciplines and especially in sensor technology researches. In this thesis, a research and development study was carried out on sensors that can measure refractive index, temperature and strain by deforming a standard single-mode telecommunication fiber. The effects of different geometric deformations on sensor performance by tapering and enlarging the the fiber diameter in sensor designs have been investigated and analyzed. In the first stage of the experimental studies, the optimum geometry of the sensor head for maximum sensitivity was determined by numerical calculations and simulation method. In further stages, experimental fabrication of fiber sensors were carried out by developing a setup using thermal method to taper the fiber. Refractive index, temperature and strain sensitivity were tested separately by establishing test setups for the fabricated fiber sensors and the sensor sensitivities were analyzed and reported. Also, a fiber sensor having two resonance dip points in the wavelength spectrum has been designed by shaping the fiber with a periodic grating pattern. This sensor that can measure temperature and strain simultaneously is novel in the literature with its unique design. By fabricating the designed sensor, the sensitivity of the sensor has been tested in experimental studies and successful results when compared with the literature have been obtained. As a result, it has been shown that with the geometric deformation techniques developed in this thesis, high-sensitivity and low-cost fiber sensors that can measure the refractive index, temperature and strain discretely or simultaneously can be easily fabricated.
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    Elastin kökenli peptit zincirlerinin yapısal geçişlerinin incelenmesi
    (Fen Bilimleri Enstitüsü, 2009) Bilsel, Mustafa; Olğar, Handan A.
    Elastin kökenli polipeptitler olarak bilinen (VPGXG)n polipeptitleri, farklı biyolojik, biyomekanik, biyokimya ve biyofizik özellikleri ile doku mühendisliğinde başta doku, mikrotüp ve nanotüp olmak üzere birçok alanda biyomateryal üretimine uygun yapıları ile dikkat çekmektedir. Bu nedenle, bu tür peptitlerin yapısının anlaşılması önem arz etmektedir. Bu amaçla, çalışmamızda elastin kökenli polipeptitlerin yapısal özellikleri bilgisayar simülasyonları yöntemiyle incelenmiştir. Simülasyonlarımız, genelleştirilmiş küme ailesinin en güçlü algoritmalarından olan multikanonik algoritma ile gerçekleştirilmiştir. Multikanonik yöntem katı halden biyofiziğe çok geniş uygulama alanına sahiptir. Çalışmamızın ilk kısmında, n=1 alınıp X aminoasiti değiştirilerek aminoasitlerin hidrofobisite skalası oluşturulmuş, ardından farklı solüsyonlarda termodinamik büyüklükler hesaplanmıştır. Son olarak, n=1, 2, 3 seçilerek küçük moleküllerden büyüklere geçişte yapısal özelliklerdeki farklılıklar belirlenmiştir.
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    Robust Refractive Index Fiber Sensor Based on Two Up-Tapers Placed in Down-Taper
    (Ankara Üniversitesi Fen Fakültesi, 2019-12-01) Navruz, İsa; Bilsel, Mustafa; Elektrik-Elektronik Mühendisliği; Mühendislik Fakültesi
    In this study, a novel tapered optical fiber sensor based on a Mach–Zehnder interferometer (MZI) for refractive index measurement is proposed. Our sensor is constructed with two up-tapers symmetrically placed in a down-taper single mode fiber. Although its waist diameter is as thick as 55 μm, the sensor can measure the refractive index. Simulation results demonstrate RI sensitivities of -94 nm/RIU and -125 nm/RIU at the lower and higher wavelength of the spectrum. The sensor is extremely robust, it can be easily manufactured and it can be used not only for RI but also for simultaneous strain and temperature measurements.