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Günümüzde su altında haberleşme için yüksek maliyetli ve çevresel donanımlara bağlı çözümler kullanılmaktadır. Öte yandan, görünür ışık ile iletişim (VLC) yeni nesil iletişim teknolojilerinden olup elektromanyetik spektrumun görünür bölgesindeki ışığı kullanarak veri iletimini amaçlayan bir teknolojidir. Radyo Frekans (RF) teknolojisinin su altı ortamda yetersiz olmasından dolayı en önemli rakibi olan VLC teknolojisi veri iletimi açısından çok daha avantajlıdır. Bu çalışmada tasarlanan VLC sisteminde ışığın doğrusal yönlülük özelliği kullanılarak sadece hedeflenen alıcı ile iletişim gerçekleştirilmektedir. Gizli bir faz kaydırmalı anahtarlama yöntemi ile verinin şifrelendiği, VLC ile veri gönderimi gizlilik protokolü üzerine çalışmalar yapılmıştır. Haberleşme, tasarlanan verici ve alıcı devreler ile gizli anahtarlama kodlaması kullanılarak çift-yönlü veri iletimi gerçekleştirilebilecek mikroişlemci aracılığıyla sağlanmaktadır. Su altı ortamında RF ve optik haberleşmeyi ayıran en önemli fark su ortamının RF tarafından iletken olarak algılanırken, VLC için dielektrik olarak algılanmasıdır. Çalışmanın odak noktası olan su ortamı için önerilen protokol, deneysel olarak farklı tuzlu derişimlere sahip su altı ortam şartlarında, alıcı – verici arası farklı yönlendirme açılarında, veri paketi teslim oranı ve gecikme süresi başarım ölçümleri dikkate alınarak test edilmiştir. Yapılan testler bir SCD sensör ile karakterize edilmiş ve simülasyonları sağlanarak motor kontrolü ve sesli uyarı ikaz sistemi geliştirilmesi hedeflenmiştir. Bu çalışmada VLC’nin su altı haberleşme performansı 1 metrelik bir akvaryumda farklı derişimlerde tuz konsantrasyonu için deneysel olarak tartışılmıştır. Today, high-cost and peripheral solutions are used for underwater communication. On the other hand, visible light communication (VLC) is one of the new generation communication technologies and aims to transmit data using light in the visible region of the electromagnetic spectrum. Due to the inadequacy of Radio Frequency (RF) technology in the underwater environment, VLC technology, which is its most important competitor, is much more advantageous in terms of data transmission. In the VLC system designed in this study, communication is carried out only with the targeted receiver by using the linear directionality of the light. Studies have been done on data transmission confidentiality protocol with VLC, in which data is encrypted with a secret phase shift keying method. Communication is provided by the designed transmitter and receiver circuits and the microprocessor, which can perform bidirectional data transmission using secret keying coding. The most important difference that separates RF and optical communication in the underwater environment is that the water environment is perceived as a conductor by RF, while it is perceived as a dielectric for VLC. The proposed protocol for the aquatic environment, which is the focus of the study, has been experimentally tested in underwater environments with different saline concentrations, at different routing angles between the receiver and transmitter, considering the data packet delivery rate and latency performance measurements. The tests performed were characterized by an SCD sensor and it was aimed to develop a motor control and audible warning system by providing simulations. In this study, the underwater communication performance of VLC is discussed experimentally for different concentrations of salt in a 1 meter aquarium.

Aydınlatma için kullanılan ışık kaynaklarını veri iletiminde kullanma fikrine dayanan Görünür Işık Haberleşmesinin (Visible Light Communication, VLC) geleceğin haberleşme teknolojileri arasında yer alması beklenmektedir. Ancak güvenilir iletişim için çokyollu yapıya sahip olduğu bilinen bina içi VLC kanallarının bilinmesi ve kestirilmesi önemlidir. Bu nedenle olası kanal karakteristiklerini incelemek amacıyla, çalışmada farklı boyutlarda çeşitli düzende yerleştirilmiş çoklu vericili odalar ele alınmıştır. Mobil kullanıcılar göz önünde bulundurularak farklı alıcı konumları için Kanal Dürtü Yanıtları ve Kanal Frekans Yanıtları hesaplanmıştır. Yapılan çalışma sonucunda, çoklu vericilerin kanalın özelliklerini değiştiren güçlü bir etken olduğu, kaynakların dağılımı ve alıcı konumu ile ilişkili frekans seçici kanallar oluştuğu gösterilmiştir. Aynı odada alıcı konumuna bağlı olarak frekans bandında tamamen farklı bir dalgalanma olabileceği, bazı frekanslarda ciddi zayıflamalar yaşandığı gözlemlenmiştir. Bu sonuç özellikle mobil alıcılar için çözüm bekleyen bir durum olarak dikkat çekmiştir. Çalışmanın sonunda çözüm önerisi olarak sunulan yönlü aydınlatma veya dar görüş açılı detektör kullanılmanın kanalın frekans seçiciliğini azaltılabileceği simülasyonlarla gösterilmiştir., Visible Light Communication (VLC), which is based on the idea of using the light sources used for lighting in data transmission, is expected to be among the communication technologies of the future. However, for reliable communication, it is important to know and predict indoor VLC channels that are known to have a multipath structure. Therefore, in order to examine the possible channel characteristics, multiple transmitter rooms with different sizes are arranged in the study. Channel Impulse Responses and Channel Frequency Responses were calculated for different receiver locations taking into account mobile users. As a result of the study, it has been shown that multiple transmitters are a powerful factor that changes the characteristics of the channel and frequency selective channels are formed related to the distribution of the sources and the receiver location. In the same room, depending on the receiver location, there may be a completely different fluctuation in the frequency band and some serious fading is observed in some frequencies. This result has attracted attention especially as a problem with pending solution for mobile users. At the end of the study, it was shown by using simulations that using directed illumination or detector with narrow field of view may reduce the frequency selectivity of the channel.

Indexed keywords Topics of prominence Abstract In visible light positioning (VLP) systems based on the received signal strengtll indicator (RSSI), tile re8ected rays from indoor surfaces distort the RSSI information and increase the positioning error. In this study, the angular diversity receiver (ADR) structure is proposed for RSSI based indoor VLP systems and positioning error is investigated together with photo-detector (PD) selection algorithm. Code division multiple access (CDMA) is used as multiplexing technique for data transfer from LEDs. The complexity of the proposed system is low due to the use of RSSI and CDMA. It has been shown that the proposed strucblre improves the mean squared positioning error performance by 10 em for the elevation angle of 60 degree, and reduces the maximum position error by 75 em at points close to the comers and walls

Bu tezde veri madenciliği ve büyük veri konuları ele alınacaktır. Büyük veriyi ele almamın nedeni, günümüzde önemli bir kavrama dönüşmesi ve zamanla neredeyse tüm sektörlerin karar aşamalarında büyük rol oynamasıdır. Birçok insan büyük verilerden bahseder, ama ne yazık ki, sadece birkaçı ne olduğunu bilir. Bu tezde, büyük verinin ne anlama geldiğini, modern dünyaya nasıl uygulanacağını ve ne tür özellikleri olduğunu öğreneceğiz. Veri madenciliği, çok miktarda bilginin analizine dayanan otomatik bir veri aramasıdır. Amaç, genel analizde imkansız olan trend ve kalıpların belirlenmesidir. Verileri bölümlere ayırmak ve sonraki olayların olasılığını değerlendirmek için karmaşık matematiksel algoritmalar kullanılır. Bu da, kurumların performansını daha doğru bir şekilde değerlendirmesine yardımcı olabilir. Dolayısıyla Veri Madenciliği yaşam standartlarımızın artması, hayatımızın kolaylaşması yolunda önemli bir kavramdır. Veri madenciliğinin her bir tekniği için çok sayıda algoritma bulunmaktadır. Algoritma sayısının çok fazla olması hangi durumda hangi algoritmanın daha başarılı olduğu her zaman kestirilememesi veri madenciliğinin zorluklarından biridir. Bu nedenle algoritmalardan bazıları ele alınacak ve hangi durumda hangi algoritmayı kullanmalıyım sorusuna cevap bulmaya çalışılacaktır., In this thesis, data mining and big data topics will be discussed. The reason why I deal with big data is that it has become an important concept and plays a major role in the decision-making process of almost all sectors. A lot of people talk about big data, but unfortunately, only a few know what it is. In this thesis, we will learn what big data means, how to apply it to the modern world and what kind of features it has. Data mining is an automated data search based on the analysis of large amounts of information. The aim is to identify trends and patterns that are impossible in the overall analysis. Complex mathematical algorithms are used to segment the data and evaluate the likelihood of subsequent events. This can help organizations evaluate their performance more accurately. Therefore, Data Mining is an important concept for increasing our living standards and making our lives easier. There are many algorithms for each technique of data mining. One of the difficulties of data mining is the fact that the number of algorithms is too high and which algorithm is not always more successful. Therefore, some of the algorithms will be discussed and an attempt will be made to find out which algorithm should be used in which case.

The Šine-Usu Inscription is the most voluminous one with 50 lines among theUyghur inscriptions. Like Tes (750) and Tariat (752-753) inscriptions, the Šine-UsuInscription also was erected in 759 in honor of Moyun Čor, the second qaghan of theUyghur Qaghanate (r. 747-759). It is still on the spot in two pieces.Most parts of the Šine-Usu Inscription are now well understood. However, thesouth and west sides are heavily damaged and there are many illegible and/orincomprehensible words and sentences in these sides. One of them is the letter groupricwgdib bIdgẄčIr in the 3rd line on the south side. The sentences containing thisletter group have been differently interpreted by the researchers. All of the readingshitherto are problematic.The author would like to regard the letter group ricwgdib bIdgẄčIr asa spelling error for ricwgidb bdIgẄčIr and suggests to read it as äbdigüči är‘soldier who recruits/drafts soldier’ (< äbdi- ‘to gather, to pick up’ + -güči ‘participlesuffix’). There are at least three examples of spelling error related to the position ofthe letter i I in the inscriptions. The sentences in question can be now read as beš yegirmikä …… tayγan költäteriltim. äbdigüči är anta ït[ïm. är k]älti “On the 15th (of the month) …… we(lit. I) gathered at the Lake of Tayγan. I sent the recruiting soldiers from there. [Thesoldiers] came”.

Date of Conference: 24 Nov.-26 Dec. 2017 Conference Name: 2017 21st National Biomedical Engineering Meeting (BIYOMUT) In Magnetic Particle Imaging (MPI), it is possible to acquire signal from the nanoparticles via applying oscillating magnetic fields in the 1 kHz -150 kHz frequency range. Though 25 kHz is commonly used, there are not enough studies on determining the optimal excitation frequency and excitation strength for obtaining images of high quality. In this study, we observed nanoparticles' response and the effect on the point spread functions (PSF) at various field amplitudes and at 10 kHz, 25 kHz and 148.5 kHz excitation frequencies. Accordingly, at 10 kHz and 25 kHz both the harmonic response of the nanoparticles and the PSFs are largely similar. On the other hand, the frequency components at 148.5 kHz are decreasing rapidly at increasing harmonics. The larger full-width at half-maximum of the obtained PSF indicates that the image resolution of this image will be lower at this frequency.

Date of Conference: 24 Nov.-26 Dec. 2017 Conference Name:2017 21st National Biomedical Engineering Meeting (BIYOMUT) Magnetic Particle Imaging (MPI) is a new imaging modality that is used for imaging the spatial distribution of superparamagnetic iron oxide nanoparticles injected as tracers. Image reconstruction in MPI can be realized directly in X-space or with a system calibration matrix. It is envisaged that obtaining a system calibration matrix would take days for a field of view of clinical purposes. On the other hand, the need for real-time imaging for applications such as interventional angiography implies that faster and more efficient reconstruction algorithms are needed than the ones at present. In this work, we present rapid system calibration with compressive sensing, and reconstruction results that have higher resolution and contrast with respect to the most common technique, Kaczmarz, using Alternating Direction Method of Multipliers (ADMM).

In this study, sensor array is designed with 4 piece of FBGs to measure temperatures using the broadband laser source. These FBGs are put into thermal medium and temperature is changed between 30 degrees C -100 degrees C with 5 degrees C steps. The changes of optic signals are examined at the optical spectrum analyzer for each 5 degrees C raise. The wavelength shifts of reflected lights for each FBGs are measured and temperature parameters of FBGs are obtained for the real time fiber optical sensor applications.

Date of Conference: 15-18 May 2017 Conference Name: IEEE 25th Signal Processing and Communications Applications Conference, SIU 2017 Magnetic Particle Imaging (MPI) is a new imaging technology that images the spatial distribution of iron oxide nanoparticles. Since the magnetic field strength that can be safely applied in MPI is limited, the field-of-view (FOV) must be divided into partial FOVs. Because the excitation magnetic field causes direct feedthrough on the receiver coil, the excitation frequency must be filtered out of the MPI signal. During this process, the nanoparticle signal at the same frequency is also lost, as a result of which each partial FOV experiences different levels of DC shift. In the standard MPI image reconstruction, these DC shifts are calculated from neighboring overlapping partial FOVs. Here, we propose a novel method that directly reconstructs the MPI image from the calculated DC shift values. Especially in the case of low bandwidth signal acquisitions, this method yields higher resolution images when compared to the standard method. The simulation results at various signal-to-noise ratios (SNR) show that the proposed method produces 6-8 dB increase in peak SNR and yields images that closely match the ideal image.

25th Signal Processing and Communications Applications Conference (SIU) -- MAY 15-18, 2017 -- Antalya, TURKEY, WOS: 000413813100200, In this paper, the performance of direct current informative subcarrier intensity modulation (DCI-SIM) which is proposed to enhance the power efficiency of subcarrier intensity modulation (SIM) is investigated in visible light communication. The BER performance of DCI-SIM is compared with SIM, pulse amplitude modulation (PAM) and, enhanced unipolar orthogonal frequency division multiplexing (eU-OFDM) for different spectral efficiencies. Using analytical derivations and simulation results, we show that the DCI-SIM is the most power efficient modulation technique among others, and that the power efficiency increases with the spectral efficiency. Furthermore, we optimize the constellation of 64-DCI-SIM and present the results., Turk Telekom, Arcelik A S, Aselsan, ARGENIT, HAVELSAN, NETAS, Adresgezgini, IEEE Turkey Sect, AVCR Informat Technologies, Cisco, i2i Syst, Integrated Syst & Syst Design, ENOVAS, FiGES Engn, MS Spektral, Istanbul Teknik Univ

In this study, a Fiber Bragg Grating (FBG) based temperature sensor is designed. Simulation is conducted to observe FBG's response to the temperature change. The temperature incident on the FBG is gradually changed from 0 degrees C to 60 degrees C in 10 degrees C steps and the frequency shifts in both RF and optical spectrum are observed.

Demirci, Neşet (Balikesir Author), Bu çalışmanın amacı üniversite öğrencilerinin ışık ve optik konuları ile ilgili kavramsal anlama düzeylerini belirlemektir. Bu çalışma, Türkiye'nin farklı bölgelerinde bulunan dört adet üniversiteden (Balıkesir Üniversitesi, Atatürk Üniversitesi, Dicle Üniversitesi ve Sütçü İmam Üniversitesi) toplam 252 kişi ile gerçekleştirilmiştir. Çalışmaya katılan öğrencilerin ışık ve optik konularıyla ilgili kavramsal anlama düzeylerini belirlemek amacıyla; görüntü oluşumu, yansıma, kırılma, ince kenarlı ve kalın kenarlı mercekler, polarizasyon, tek yarıkta kırınım ve çift yarıkta girişim konularını kapsayan optik kavram testi kullanılmıştır. Verilerin analizi sonucunda, üniversite öğrencilerinin ışık ve optik konularında (görüntü oluşumu, yansıma, kırılma, ince kenarlı ve kalın kenarlı mercekler, polarizasyon, tek yarıkta kırınım ve çift yarıkta girişim) birçok problemleri olduğu ve öğrencilerin kavramsal anlama düzeylerinin de düşük olduğu tespit edilmiştir. Kavramsal anlama düzeylerinin düşük olmasında öğrencilerin sahip oldukları kavram yanılgılarının büyük etkisinin olduğu düşünülmektedir, The purpose of this study is determining university students' conceptual understanding about the subjects of light and optics. This study has been carried out by a total of 252 university students from four different universities (namely, Balıkesir University, Ataturk University, Dicle University and Sütçü İmam University) all over the Turkey. In order to determine students' conceptual understanding and their difficulties on the subjects of light and optics, The Light and Optics Concept Evaluation Test, which includes the subjects of image formation, reflection, refraction convex and concave lenses, polarization, single-slit diffraction and the double slit interference, has been used. When analyzing the data that obtain from all of the subjects, it's been seen that university students have a lot of problems all concepts related to the subjects of light and optics and also found that their level of conceptual understanding were too low. It's been considered that the students' misconceptions could have really big effects about their conceptual understanding and their difficulties about the related topics

This paper presents a study dealing with the experimental and theoretical analysis of a flat plate solar air heater. The air collectors were tested experimentally for the tilt angle of 35$^{\circ}$ and 2 m $s^{-1}$ air velocity, and ambient temperature, inlet temperature, outlet temperature, absorber plate temperature, bottom plate temperature, solar radiation, air velocity, and airflow velocity from the duct were measured. The outlet air temperature and energy and exergy efficiencies of the collector were calculated theoretically. The results showed that the collector has the maximum mean outlet temperature for the airflow velocity of 1 m $s^{-1}$, duct height of 0.001 m, triple glass cover, and length of 3 m; the maximum mean energy efficiency for the airflow velocity of 4 m $s^{-1}$, duct height of 0.04 m, triple glass cover, and length of 1 m; and the maximum mean exergy efficiency for the airflow velocity of 1 m $s^{-1}$, duct height of 0.005 m, triple glass cover, and length of 3 m. This study demonstrated the superiority of exergy analysis over energy analysis before the decision regarding design parameters.

The aim of this work is to present a theoretical study of a vertical junction silicon solar cell under monochromatic illumination. By solving the continuity equation and using a one-dimensional model in frequency modulation, we derive the analytical expressions of both excess minority carrier density and photovoltage. Based on these expressions, the solar cell capacitance was calculated; we then exhibited the effects of both illumination wavelength and incidence angle on the solar cell capacitance.

The problem of steady laminar mixed convection heat transfer about a vertical cone embedded in a porous medium with high porosity was studied numerically, taking into account the radiation--conduction effect. The fluid was assumed to be incompressible and dense. The nonlinear coupled parabolic partial differential equations governing the flow were transformed into nonsimilar boundary layer equations, which were then solved numerically using the Keller box method. The effects of the exponent in the power law variation of the free stream velocity m, the mixed convection parameter Ri, the radiation--conduction parameter Rd, the surface temperature parameter qw, and Forchheimer parameter g on the velocity and temperature profiles, as well as on the local skin friction and local heat transfer, are presented and analyzed. The validity of the methodology and analysis was checked by comparing the results obtained for some specific cases with those available in the literature.

Verification of Specific Absorption Rate measurement system is necessary before determining the Specific Absorption Rate value of mobile phones. The Specific Absorption Rate measurement system, including the electric field probe, the tissue equivalent liquid and robot used for positioning the probe and also the special software, should be validated in order to check whether it works correctly or not at the test frequency. A flat phantom and a reference dipole antenna are used for the system verification. The reference dipole antenna is placed at the bottom of the flat phantom. So, electric field is formed inside the liquid by applying a known power is delivered to dipole antenna to the tissue equivalent liquid. In this study, the construction, characterization and validation measurements of reference dipole antenna which is one of the important components of validation measurements will be discussed., Mobil telefonların Özgül Soğurma Oranı (Specific Absorption Rate) değerinin belirlenmesi için yapılan ölçümler öncesinde ölçüm düzeneğinin doğrulanması gerekir. SAR ölçümlerinde kullanılan robotun, elektrik alan probunun, eşdeğer doku sıvısının ve ölçme programının bir arada doğru olarak çalıştığını kontrol etmek için doğrulama çalışması yapılır. Doğrulama ölçümlerinde, kutu fantomun alt kısmına referans bir dipol anten yerleştirilir. Böylece eşdeğer sıvı üzerine değeri bilinen bir güç uygulanarak sıvı içerisinde elektrik alan oluşması sağlanır. Bu çalışmada doğrulama ölçümlerinin önemli bileşenlerinden biri olan dipol anten yapımı, karakterizasyonu ve doğrulama ölçümlerinden bahsedilecektir.

Monopole and dipole antennas have been commonly used especially in wireless communications. Therefore, the electrical properties of these types of antennas on their location affect the antenna radiation pattern which is important for efficiency of the communication system. In this study, for different electrical properties with ground planes -very dry, dry, wet and ice- on which a half wave dipole antenna's radiation pattern how changed was analysed by utilizing from the method of moments solution of Hallen's integral equation and image theory with reflection coefficient approximation.

Bu tez İbn Heysem‟in optik kitabı Kitâb el-menâzir‟de ortaya koyduğu yeni bilim anlayışının ilkeleri ile yeni bilim yönteminin özelliklerini incelemeyi hedefleyen bir çalışmadır. Bununla İbn Heysem‟in kendisinden önce hâkim bilim yöntemi olmamış Arşimet‟in matematik-fizik terkip yöntemini geliştirip kendisinden sonra gelen bilim adamları aracılığıyla Newton‟a kadar taşınmasını sağlama yolundaki etkisi araştırılmıştır. Araştırmanın hedefine uygun olarak Kitâb el-menâzir başta olmak üzere İbn Heysem‟in optik, matematik ve felsefe eserlerinde geliştirdiği bilim anlayışı ve yönteminden bahsettiği bölümler esas alınmıştır. This thesis is a study aimed to investigate the principles of Ibn al-Haytham‟s new concept of science and properties of the methods he has used. The main target is to demonstrate that Ibn al-Haytham has developed a method which had stayed weak through the history of science, namely the Archimedean method of combination of physics and mathematics, and his role in leading this method to be delivered up to Newton under favor of the succeeding scientists of both Islamic and Latin worlds.The method of the thesis has been designated to focus on certain parts and chapters in optical, mathematical and philosophical works of Ibn al-Haytham of which Kitâb al-Manazir holds the main part.

The study demonstrates the metamaterial characteristics of the arrays containing dielectric resonators by evaluating the permittivity and permeability coefficients of the array structures in rectangular waveguide and free space. For this purpose, the array with two closely spaced dielectric resonators is setup and placed both in a rectangular waveguide and free space one by one. The scattering parameters in both structures are extracted with full-wave simulations (CST Microwave Studio) and supported with measurement results. Then, the effective relative permittivity and permeability values are obtained with the deembedding technique and retrieval method. According to the results, the structures show double negative (DNG) characteristics at some frequencies. Therefore, the array with dielectric resonators is shown to have metamaterial characteristics. Besides, the DNG frequencies of both (waveguide and free space) structures are found to be consistent to each other. This means that the metamaterial behaviour of the dielectric resonator array is highly insensitive to the wave excitation where TE10 and TEM modes are excited in rectangular waveguide and free space, respectively.

The diffraction mechanism is used for field prediction in both light and shadowed regions. Slope and amplitude diffraction coefficients are vital to predict the field strength at the receiver accurately. In this paper, amplitude and slope diffraction coefficients for one of the ray theoretical models, the slope uniform theory of diffraction with convex hull (S-UTD-CH) model, are analyzed. Moreover, diffraction coefficients are given for knife-edge and wedge structures.

Behavioral responses of Cataglyphis aenescens foragers to various monochromatic light stimuli were tested. Foragers were trained to associate lights of 370 (UV), 440 (blue), 540 (green), and 640 nm (red) with a food reward on a circular orientation platform and were then tested to determine the threshold intensity values of these wavelengths they could perceive. Foragers significantly responded to all wavelengths at training intensities but their homeward orientation diminished with decreasing stimulus intensity. The results showed that UV and green lights could be perceived at lower intensities compared to blue and red lights. Foragers were further trained in a Y-maze apparatus to discriminate 2 monochromatic light stimuli of the same wavelength but different in their intensities. The results showed that they failed to make a significant discrimination except for the 440 and 640 nm pairs. Overall results revealed a broad spectral sensitivity for foragers ranging from at least 370 nm (UV) to 640 nm (red) mediated by both chromatic and achromatic cue perception.

The results of studies of broadband light transmission through a fiber loop and a double loop under the effect of nonlinear refractive index are presented in this paper. Fiber loop and double loop transmission/reflection vs. a coupler splitting ratio at various powers of the light with a spectral width of approximately 35 nm are studied and high efficient nonlinear light switching is demonstrated. It is shown that a double loop formed by consecutive connecting 2 fiber loops allows us to exclude the strong spectral dependence of light transmission/reflection and to distribute input light equally between them. Such all-fiber devices can find a real application in broadband systems of optical communication and data processing.

Our main aim was to investigate variations in the refractive index of a solution during chemical reaction. The variation of refractive index was measured through the entire acid--base titration process, especially near the equivalence point. To determine the equivalence point, the conductivity of the solution and the refractive index were measured simultaneously. In this preliminary study, sodium hydroxide and hydrochloric acid were used as the base and the acid solution, respectively. To measure the refractive index variation, a fiber-optic refractive index sensor was designed. The fiber-optic probe was dipped into the solution and acted as a refractive index sensor according to Fresnel's fundamental reflection law. A conductometer, a lab-made fiber-optic refractive index sensor ensemble, and a lab-made optical drop counter were each connected to a computer via an analog digital converter and the data acquisition was performed with the LabVIEW program. The equivalence point was derived easily from the refractive index data for the sodium hydroxide solution with different molarities of hydrochloric acid. In our opinion, the measurement of the variation of the refractive index during this kind of chemical reaction is more sensitive than the conductometric measurement.

A Gaussian laser pulse propagating through plasma in the presence of a magnetic wiggler produces third-harmonic radiation. The wiggler's magnetic field provides additional momentum required for phase matching. The required wiggler wave number is sensitive to pulse duration and amplitude. The efficiency of the process is significant at the instant at which the phase matching condition is satisfied.

A novel compact omnidirectional coplanar waveguide (CPW)-fed antenna with band-notched characteristics has been designed and analyzed. The proposed ultra-wideband (UWB) antenna has a simple structure. A ring-shaped radiating patch is excited by a CPW feed line. By creating 2 square slots on the top corners of the antenna, a new resonance is excited and the bandwidth is enhanced. The band-notched function is achieved by applying 2 rectangular stubs to the ground plane structure. The proposed antenna occupies a small size of 20 x 20 x 1 mm3 and covers a wide frequency range of 3.1--14 GHz, except for 5--6 GHz, where the interference of the Wireless Local Area Network (WLAN) the UWB is overcome. An omnidirectional radiation pattern and relatively constant gain is observed for the proposed antenna.

An improved metamaterial antenna, with a compact size of 27.8 x 31.9 x 0.794 mm3, fed by an offset-microstrip line, is proposed. The total size is slightly reduced and the measured impedance bandwidth is 4.08-7.83 GHz for a return loss of \mid S11\mid < -10 dB. Compared with the original patch antenna, the bandwidth of the proposed antenna is 550 MHz broader and has a lower resonant frequency. The simulated gain of the antenna is more than 2 dB, with a peak of about 6 dB at 6.8 GHz. Moreover, the antenna has strong radiation in the horizontal direction for some specific applications within the entire band.

22nd IEEE Signal Processing and Communications Applications Conference (SIU) -- APR 23-25, 2014 -- -- Karadeniz Teknik Univ, Trabzon, TURKEY, WOS: 000356351400128, Measurement of refractive index which is one of the distinctive properties of materials is commonly used in many fields such as quality control of food industry, biomedical applications, biochemical analysis and measurement of environmental pollution. From the refractive index measurement methods, the one based on fiber optic stands out with their provided advantages. In this study, firstly, a simple, reliable and highly sensitive Fresnel reflection based fiber optic refractometer was setup, then the refractive indexes of various liquids were measured using this setup at different times. When the measurement results are compared with material science data sheet (MSDS) values, the percent error was found to be less than %1. Moreover, the long term stability of ethanol's refractive index was examined and the refractive index variation of salt-water was obtained as a function of the salt concentration., IEEE, Karadeniz Tech Univ, Dept Comp Engn & Elect & Elect Engn

Bu çalışmada, amorf mikroskop camlar üzerine spin kaplama yöntemi kullanılarak ZnO ince filmleri üretilmiş ve bufilmler 350 oC ile 850 oC arasında değişen sıcaklıklarda tavlanmışlardır. Tavlamalar 50 oC’lik aralıklarlagerçekleştirilmiş ve iki farklı (0.5 ve 8 saat) tavlama süresi kullanılmıştır. Bütün numunelere ait XRD, SEM ve UVVisspektrumları alınarak numunelere ait optik ve yapısal özellikler analiz edilmiştir. 400 oC’de sekiz saat tavlanannumunede sadece (100) yönünde kristallenme gözlenmiştir. 800 oC ve 850 oC tavlamaları SiO2 ve Zn2SiO4 ilebağlantılı iki faz üretmiştir. Yapılan deneyler tavlama sıcaklığı ve süresinin genelde ZnO nanoyapılarının çaplarınıartırdığını göstermiştir. Orta sıcaklıklarda (350-600 oC) tavlanan numunelerde 370 nm’de (3.36eV) konuşlanmış birsoğurma bandı gözlenirken bu pik 650 oC’den sonraki tavlama sıcaklıklarında 290 nm’de yeni bir soğurma pikioluşturmuş ve bu yeni pikin de SiO2 fazından kaynaklandığı tespit edilmiştir. 800 oC’de 8 saat tavlanmış numunelerdeSiO2 soğurma pikinde 10 nm’lik bir kırmızaya kayma tespit edilmiştir., In this study, ZnO thin films on amorphous microscope glasses were fabricated using the spin coating method and annealed at temperatures ranging from 350 o C to 850 o C. Annealings have been performedat these temperatures in 50o C increaments and for two annealing durations (0.5 and 8 hours). XRD, SEM and UV-VIS spectra of all the samples have been given. Optical and structural properties of the produced films have been evaluated. The sample annealed at o C for eight hours was crystallized in only one (100) direction. Annealing at 800 o C and 850 o C created new phases related to SiOand ZnSiO , respectively. It has been found that the annealing temperature and duration generally increased the ZnO nanostructures’ diameter. The UV-VIS spectra of the samples for moderate temperatures (350-600 o C) had an absorption band at 370 nm (3.36eV), whereas these peaks disappeared after 650 o C annealing, producing a new absorption peak situated at 290 nm which could be attributed to the SiO phase. In case of the sample annealed at o C for 8 hours, SiO absorption peak has 10 nm redshift.

Date of Conference: 22-24 April 2010 One of the important techniques used for three dimensional television (3DTV) is holography. In holographic 3DTV, spatial light modulators (SLM) are used as the display device. SLMs that provide the most limited modulation are the binary SLMs, since only two different values can be assigned to their pixels. An important signal processing problem arising here is the determination of the binary signal to be written on the SLM among the possible ones such that the desired light field is generated to the best extent. Many of the proposed methods do not produce satisfactory results in terms of error rate, computational performance or light efficiency. We propose an optical setup to be placed in front of the binary SLM and the associated signal processing algorithm. The proposed system uses a 4-f setup and a periodic mask is placed to the Fourier plane. As a result, the binary SLM is convolved with a series of regularly spaced impulse functions and we get a new SLM which is smaller in pixel count compared to binary SLM but which can provide 16-bit full complex modulation. It becomes easier to generate the desired light field with this new SLM. Also, the required computations are carried out in a fast manner to enable real-time operation. ©2010 IEEE.

Bu tez çalışmasında DBSCAN ve OPTICS algoritmaları, yazarlarının makalelerinde ortaya koyduğu sözde kodlar temel alınarak kodlanmıştır. Tek bilgisayar üzerinde gerçekleştirilen çalışmalarda komşuluk sorgularının çok zaman aldığı görülmüş ve bu sürenin kısaltılması için R*-Tree veri yapısı kullanılmıştır. DBSCAN algoritmasının paralelleştirilmesi için LAM/MPI kütüphanesi kullanılmıştır. DBSCAN uygulamasının en çok zaman harcayan kısmı olan komşuluk sorguları, LAM/MPI yardımı ile tüm bilgisayarlara eşit şekilde paylaştırılarak yapılmıştır. 3 farklı veri seti ile gerçekleştirilen testlerde DBSCAN algoritmasının paralelleştirmeye elverişli olduğu ve paralel çalışan DBSCAN‟in Amdahl Kanunu‟na uygun olarak çalışma süresinin kısaldığı, bununla birlikte küme oluşturma performansının ve kalitesinin etkilenmediği görülmüştür. Toplam 6 bölümden oluşan tezin birinci bölümünde genel kavramlardan bahsedilmiştir. İkinci bölümde veri madenciliğinin genel tanımı, uygulama alanları, veri madenciliği süreci ve veri madenciliği tekniklerinden bahsedilmiştir. Üçüncü bölümde kümeleme analizinin türlerinden, yoğunluk tabanlı kümeleme yöntemleri ağırlıklı olmak üzere bahsedilmiştir. Dördüncü bölümde paralel hesaplamanın amacı, paralel bilgisayar bellek mimarileri, paralel programlama modelleri ve paralel program tasarımından bahsedilmiştir. Beşinci bölümde paralel DBSCAN uygulamasının geliştirilme amacı, geliştirme ortamı, kullanılan araçlar, kullanılan veri setleri ve uygulamanın geliştirme adımlarından bahsedilmiştir. Altıncı ve son bölümde deneysel sonuçlar tablolar ve grafiklerle verilmiş ve elde edilen sonuçlar irdelenmiştir. Ayrıca bu konuda çalışma yapacak araştırmacılar için öneriler sunulmuştur., In this master thesis, DBSCAN algorithm and OPTICS algorithm have been coded by taking the pseudo-codes; that the writers set forth in their articles, as the basis. It has been noticed that neighborhood queries take too long time on the works carried out on a single computer and R*-Tree data structure is used in order to shorten this period. LAM/MPI library has been used to parallelize DBSCAN algorithm. Neighborhood queries are the part that spends most of the runtime of the DBSCAN application, and this has been performed by equally distributing to all the computers by the help of LAM/MPI. It has been evaluated in the tests; which had been implemented by 3 different data sets, that DBSCAN algorithm is suitable for parallelization and the runtime period of DBSCAN that works parallelly is shortened in accordance with Amdahl Principle. The general concept has been mentioned in the first section of the thesis that consists of 6 chapters. In the second chapter, general definition of data mining, its application areas, data mining process and techniques of data mining have been explained. Third chapter mainly encloses density based clustering methods that is one of the types of clustering analysis. Fourth chapter includes the objective of parallel programming, parallel computer memory architecture, parallel programming models and parallel program design. Fifth chapter consist of the development objective of parallel DBSCAN application, development environment, the tools used, the data sets and the development steps of the application. In the sixth and the last chapter, experimental results have been given with tables and graphics and attained results have been examined. Besides, suggestions have been presented for those who want to make research on this subject.

Araştırmanın amacı, ortaöğretim 9. sınıf öğrencilerinin düzlem ayna konusuna ilişkin ön bilgilerini ve kavram yanılgılarını belirlemektir. Bu amaçla veri toplama sürecinde; “Aynalar Ünitesi Kavramsal Anlama Testi” ile “Yarı Yapılandırılmış Görüşme Formları”ndan yararlanılmıştır. Kavramsal anlama testinde; düzlem ayna konusunun “görüntü oluşumu”, “görüntü özellikleri” ve “görüş alanı” alt başlıklarına ilişkin toplam 4 soru yer almaktadır. Test iki farklı lisede eğitim gören toplam 310 öğrenciye uygulanmıştır. Kavramsal anlama testinin değerlendirilmesi aşamasında; öncelikle araştırmacılar tarafından soruların doğru yanıtları oluşturulmuş, öğrencilerin verdikleri yanıtlar “kodlanabilir”, “kodlanamaz” ve “yanıtsız” olarak kategorilendirilmiştir. Kodlanabilir yanıtlar ise “bilimsel olarak kabul edilebilir” ve “bilimsel olarak kabul edilemez” başlıkları altında gruplandırılmıştır. Kavramsal anlama testi ve toplam 16 öğrenci ile gerçekleştirilen görüşmelerden elde edilen veriler incelendiğinde; “gözlemcinin konumu ilegörüntü ilişkisi”, “düzlem aynada görüntünün yeri”, “cisim ile görüntü arasındaki ilişki”, “görüntünün sahip olduğu özellikler” ve “görüş alanının bağlı olduğu faktörler” konularında öğrencilerin kavram yanılgılarına sahip olduğu belirlenmiştir. Öneriler bölümünde ise kavramsal değişim sürecinde düzlem ayna konusuna ilişkin olarak öğretmenler tarafından etkin bir biçimde kullanılabilecek deneysel aktivitelere yer verilmiştir

IEEE 17th Signal Processing and Communications Applications Conference -- APR 09-11, 2009 -- Antalya, TURKEY, WOS: 000273935600074, This paper proposes the use of single sideband modulation technique with Gaussian and band pass fillers for the analysis of the thermal lens fringe to obtain the map of the refractive index change. Maps of the refractive index and phase change are achieved by using single side band modulation technique with Gaussian and band pass filters. Consequently it is seen that single side band modulation technique with Gaussian filter shows more accurate results., IEEE

A novel method based on the effective-index method which reduces the optical rib waveguide having a two-dimensional cross-section into four separate one-dimensional slab waveguides is presented. In order to test the accuracy of proposed method, firstly, dimensions of the rib waveguide are changed so that the two rectangular waveguides with different aspect ratios are obtained and then these structures are analyzed with the proposed method. Secondly, the preceding results are compared with the results of the two rectangular waveguides analyzed by the conventional effective-index method. In consequence of this comparison, it can be seen that there is a good agreement between the results of the proposed method and the effective-index method, especially for square cross-sectioned waveguides.

3D laser scanning systems have been used in many industrial applications. They provide depth information of an object so that it can be processed by a computer. Unfortunately, laser scanners can not be used reliably on metallic surfaces and shiny marble stones due to scattering of the laser line on the surface. To overcome this problem, either the light intensity of the environment is adjusted or the surface is covered with a powder to decrease the scattering on the surface. In this study, we propose a solution to overcome the scattering problem of line lasers by using color indices. This way, shiny surfaces can also be scanned reliably. To test our method, we also developed a prototype 3D laser scanner system and provide the results. © 2006 IEEE. 2006 IEEE 14th Signal Processing and Communications Applications -- 17 April 2006 through 19 April 2006 -- Antalya -- 69461

Bu çalışmada, veri madenciliğinde güncel kümeleme algoritmalarından DBSCAN, OPTICS ile geçmişi daha eskilere dayanan K-means algoritması karşılaştırılmıştır. Karşılaştırma sentetik veritabanı üzerinde gösterdikleri küme bulma performansları değerlendirilerek yapılmıştır. Sonuçta, yakın zamanda literatüre giren DBSCAN ve OPTICS algoritmalarının K-means algoritmasından daha üstün küme oluşturma özelliklerine sahip olduğu tespit edilmiştir., DBSCAN and OPTICS are two recent clustering algorithms on data mining. In this study, these two algorithms and K-means which is one of the oldest clustering algorithms are compared. Comparison is based on cluster discovery performance on synthetic database. Consequently, two recent clustering algorithms DBSCAN and OPTICS are performed superior accuracy and cluster discovery ability over K-means algorithm.

ÖZET Bu çalışmanın amacı açık kanallı optik haberleşme sistemlerinin incelenmesi, bu konuda günümüze kadar yapılan çalışmaların araştırılarak eksikliklerin tespit edilmesi ve araştırma sonucu elde edilen bilgiler ışığında açık kanallı optik haberleşme metoduyla çalışan bir sistemin tasarımının önerilmesidir. Bu çalışmada araştırma, inceleme, deney ve gözlem metotları kullanılmıştır. Birinci bölümde bu çalışmanın önemi, amaç ve kapsamı açıklanmıştır. İkinci bölümde bu konuda kaynak araştırması yapılarak literatürdeki mevcut çalışmalar incelenmiş, elde edilen bilgiler özet şeklinde sunulmuştur. Üçüncü bölümde bu konudaki teorik bilgiler sunulmuş ve bu bilgiler ışığında bir sistem tasarlanmış, tasarlanan sistemde bazı donanımsal gereklilikler yazılımsal açıdan çözülmüştür. Kullanılan bu yöntemin tartışması 4. Araştırma Sonuçları ve Tartışma başlıklı bölümde sunulmuştur. Sistemin çalıştırılmasından sonra sistem üzerinde ayrıntılı analizler yapılarak bu analizlere ait tablolar ve şekiller üzerlerinde yorumlar yapılarak sunulmuştur. Dördüncü bölümde çalışmada elde edilen araştırma sonuçları ve bulgular verilmiş, tasarlanan sistemin geliştirilebilir yanları öneriler ile birlikte verilmiştir. ANAHTAR KELİMELER Optik, optik haberleşme, kızılötesi, fotodiyot, ışın verici diyot 11 ABSTRACT The purpose of this work is to investigate optical through the air communication systems, to determine the deficiency on this subject making a research about all works up to date and to suggest a system working with optical through the air communication method by using the information of this research. Investigation, research, test and observation methods are used in this work. In first chapter, the purpose, importance and scope of this work is given. In second chapter, the works in the literature of this subject are investigated making a source research and the information obtained from this investigation is given. In third chapter, the theoretical information of this subject is given and a system is projected by using this information and some hardware problems are solved by the help of software. The discussion of this method is made in fourth chapter. After operating this system, tables and figures on detailed analysis of this system are given by making some explanations. In fourth chapter, the results of this work are explained and some alternatives about improvement of this system are given. KEYWORDS Optics, optical communication, infrared, photodiode, light emitting diode 96

İnsan vücudunun en önemli duyu organı olan göz, insanların çevresini algılamasını sağlayan dünyaya açılan penceresi olarak bilinmektedir. Gelişen teknolojinin ulaştığı son noktada dahi gözün sahip olduğu özellikleri ve fonksiyonel kapasitesine ulaşamamıştır. İnsan gözün birinin zarar görmesi hatta küçük bir sorun bile yaşanması halinde tedavisi oldukça güç ve yaşam kalitesini doğrudan etkilemektedir. Göz kusurlarının tedavisinde kullanılan gözlükler insanların daha iyi görmesini ve günlük hayatını konforlu bir şekilde sürdürebilmesine imkân sağlamaktadır. Bu ihtiyaç optik sektörünün oluşmasını sağlamıştır. Tüm dünyada ve ülkemizde büyük bir hızla gelişen optik sektörü, kişilerin ihtiyaçlarını karşılamak dışında moda ile de etkileşim içinde olan bir sektör haline gelmiştir. Bu çalışmada optik sektörünün kapsamını ve ülkemizdeki Optisyenlik mesleğinin gelişmesi, değerlendirmesi ve Ankara ili özelinde yaşanan gelişmeler detaylı olarak incelenmiştir., The eye organ, the most important sensory organ of the human body, is known as the window to the world that allows individuals to perceive their surroundings. The latest advances in technology have not yet reached the features and functional capacity of the eye. Even a slight damage to any single one of the eyes leads to complications very difficult to correct and affects the quality of life directly. The glasses used in the treatment of eye defects allow people to see better and maintain their daily life comfortably. This need led to the foundation of the optics industry. The optics industry, which is developing rapidly all over the world and in Turkey, has become an industry that interacts with fashion, in addition to meeting the needs of people. In this study, the scope of the optics industry, and the development of the optician profession in Turkey was investigated and evaluated in detail within the scope of developments in Ankara province.