Optical characterization of Ga2SeS layered crystals by transmission, reflection and ellipsometry

Optical properties of Ga2SeS crystals grown by Bridgman method were investigated by transmission, reflection and ellipsometry measurements. Analysis of the transmission and reflection measurements performed in the wavelength range of 400-1100 nm at room temperature indicated the presence of indirect and direct transitions with 2.28 eV and 2.38 eV band gap energies. Ellipsometry measurements were carried out in the 1.2-6.0 eV spectral region to get information about optical constants, real and imaginary parts of the pseudodielectric function. Moreover, the critical point (CP) analysis of the second derivative spectra of the pseudodielectric constant in the above band gap region was accomplished. The analysis revealed the presence of five CPs with energies of 3.87, 4.16, 4.41, 4.67 and 5.34 eV

Annealing Effect on Dark Electrical Conductivity and Photoconductivity of Ga-In-Se Thin Films

Dark-conductivity and photoconductivity properties of thermally evaporated Ga-In-Se (GIS) thin films were investigated in the temperature range of 80-430 K. All measurements were performed on as-grown and annealed GIS thin films at 300 and 400 degrees C to get information about the effect of the annealing temperature on the conductivity properties. Room temperature conductivity was obtained as 1.8 x 10(-8) Omega(-1) cm(-1) for as-grown films and increased to 3.6 x 10(-4) Omega(-1) cm(-1) for annealed films at 400 degrees C. Analysis of the dark-conductivity data of as-grown films revealed nearly intrinsic type of conductivity with 1.70 eV band gap energy. Temperature dependent dark conductivity curves exhibited two regions in the 260-360 and 370-430 K for both of annealed GIS films. Conductivity activation energies were found as 0.05, 0.16 and 0.05, 0.56 eV for films annealed at temperatures of 300 and 400 degrees C, respectively. The dependence of photoconductivity on illumination intensity was also studied in the range from 17 to 113 mW/cm(2)

Economic and social structures of water buffalo farming in Muş province of Turkey

ABSTRACT -The purpose of this study was to analyse the socio-economic structure of water buffalo farming in the province of Muş, in Turkey. The stratified sampling method was used to calculate sample size of buffalo farms in the Central, Korkut, and Hasköy districts of Muş province, where buffalo farming is widespread. Data were collected from the 94 farms by surveys in the 2013 production period. A single budget analysis method was used to calculate production cost and profit for water buffaloes. Plant production constituted 37.85% of the gross production value, while animal production accounted for 62.15%. The biggest share in the gross production value derived from water buffalo farming (45.71%). Fixed and variable costs were 51.44% and 48.56% of the production cost (USD11691.06), respectively. The largest part of the variable cost was the feed cost (75.81%). The cost of per kilogram buffalo milk in the region was calculated as USD0.64. Consequently, it is important to ensure the continuation of breeding studies to increase milk yield, giving information to farmers about modern techniques, developing policies to increase the scale of the farms, and implementing regional and national policies to increase awareness of buffalo milk and milk products

FPGA TABANLI DİJİTAL HABERLEŞME SİSTEMLERİNİN SYSTEM GENERATOR ARACI İLE ANALİZİ

Sayısal haberleşme sistemlerinde, verici tarafından iletilen verinin alıcı tarafına minimum hata ile ulaştırılması arzu edilmektedir. Ancak iletilen veri, kullanılan modülasyon tekniği, kodlama ve kanal yapısına dayalı çeşitli sebeplerden dolayı bozulmaya maruz kalmaktadır. Bu bozulma, iletim süresince alıcıya ulaşan hatalı bitlerin sayısının bütün bitlere oranı “bit hata oranı” BER olarak tanımlanmaktadır ve bu oran iletişim sisteminin kalitesini belirlemektedir. Günümüzde yapılan akademik çalışmalarda haberleşme sistemlerini analiz etmek için genellikle Matlab benzetim programları kullanılmaktadır. Ancak, bu şekilde yapılan ölçümlerin zaman alıcı olmasının yanı sıra benzetim programlarının da gerçek bir haberleşme sistemini tam olarak temsil etmediği düşünülmektedir. Bu sebeple, bir haberleşme sisteminin FPGA gibi paralel çalışan hızlı modüllerle gerçekleştirilmesi ve bu sistem üzerinden gerekli ölçümleri yapılmasının daha hızlı, gerçeğe yakın ve özgün olacağı düşünülmektedir.Bu çalışma ile BPSK (iki seviyeli faz kaydırmalı anahtarlama) ve QPSK (dört seviyeli faz kaydırmalı anahtarlama) modellerine uyarlanabilen FPGA (Alan Programlanabilir Kapı Dizileri) tabanlı bir gömülü haberleşme sistem tasarımı gerçekleştirilmiştir. Tasarlanan sistem daha sonra FPGA tabanlı sistemleri analiz etmek için kullanılan Xilinx firmasının geliştirdiği System Generator aracı ile analiz edilmiştir. İletilen veri minimum hata ile tekrar elde edilmeye çalışılmıştır

Design and Implementation of Real Time Monitoring and Control System for Distributed Robotic Systems Supported with IOS/Android Application

In this study, a real time monitoring and control of the working parameters of distributed robotic systems used in manufacturing processes is presented. Additionally, a fault diagnosis and protection system is developed in the control and monitoring system to prevent possible errors during the working process. Unlike the conventional monitoring and control systems, Android/IOS based smart phones and tablets are used besides SCADA and the process is supported by cameras. 3 different robotic systems are used in the study and electrical, electronic and mechanical prototypes are designed for each of them. Thus, a complete robotic system being able to perform real time monitoring and control for industrial manufacturing processes that is supported by smart phone applications and fault diagnosis and protection system is developed successfully

Design and implementation of a training set for distributed system and mechatronic applications: project based learning

Danas, s razvojem informatičke tehnologije, razvijeni su suvremeni i pouzdani uređaji za korisnike i upravljanje sustavom. Najviše korišteni su paneli za operatera i regulatori logike za programiranje. Programiranje ovih uređaja, učenje kako komunicirati s kontrolnim i hardverskim instalacijama postalo je vrlo važno posebice za tehničko osoblje i studente inženjerstva. U ovom radu, razvijeni su setovi za učenje tehnika za automatizaciju i upravljanje koji se uvelike rabe u industrijskim aplikacijama. U tim su se setovima za upravljanje koristili regulator logike za programiranje (PLC) i sučelje između čovjeka i stroja - human machine interface (HMI). U setovima za učenje paralelno su se uspoređivale i uvježbavale tehnike automatizacije i regulacije kao P, PI i PID. U isto vrijeme, s tom su se aplikacijom pokušavale popraviti vještine i sposobnosti logičkog programiranja obučavanih studenata. U svrhu mjerenja i evaluacije, formirana je grupa od 40 ljudi - 18 pripadnika tehničkog osoblja iz industrijskog sektora, 14 studenata inžinjerstva automatizacije i 8 studenata pripremanih za rad prije stjecanja diplome, čije su se sposobnosti mjerile po završetku obuke.Nowadays, with the development of information technology, real-time and reliable devices have been developed for users and system control. Commonly used ones are programmable logic controller and operator panels. Programming of these devices, learning the communication with the controller and the hardware installations have gained great importance especially for technical staff and engineering students. In this study, automation and control technique training sets were developed for the applications used widely in industrial applications. In the training sets, programmable logic controller (PLC) and human machine interface (HMI) were used for the control. With the training sets both automation education and control techniques such as P, PI, and PID are compared. At the same time, skills and logical programming abilities of the students studying in the training were attempted to be improved with this application. In order to measure and evaluate, 18 technical staff working in the industrial sector, 14 students studying automation engineering and eight students studying pre-license training, a group of 40 people in total was formed and performances were measured at the end of the training

Determination of optical parameters of Ga0.75In0.25Se layered crystals

The optical properties of the Ga0.75In0.25Se crystals have been investigated by means of transmission and reflection measurements in the wavelength range of 380-1100 nm. The analysis of the results performed at room temperature revealed the presence of optical indirect transtions with band gap energy of 1.89 eV. The variation of the band gap energy as a function of temperature was also studied in the temperature range of 10-300 K. The rate of change of band gap energy (? = 6.2 x 10(4) eV/K) and absolute zero value of the band gap (Egi(0) = 2.01 eV) were reported. The wavelength dependence of the refractive index was analyzed using Wemple and DiDomenico, Sellmeier and Cauchy models to find the oscillator energy, dispersion energy, oscillator strength and zero-frequency refractive index values. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Composition-tuned band gap energy and refractive index in GaSxSe1-x layered mixed crystals

Transmission and reflection measurements on GaSxSe1-x mixed crystals (0 <= x <= 1) were carried out in the 400-1000 nm spectral range. Band gap energies of the studied crystals were obtained using the derivative spectra of transmittance and reflectance. The compositional dependence of band gap energy revealed that as sulfur (selenium) composition is increased (decreased) in the mixed crystals, band gap energy increases quadratically from 1.99 eV (GaSe) to 2.55 eV (GaS). Spectral dependencies of refractive indices of the mixed crystals were plotted using the reflectance spectra. It was observed that refractive index decreases nearly in a linear behavior with increasing band gap energy for GaSxSe1-x mixed crystals. Moreover, the composition ratio of the mixed crystals was obtained from the energy dispersive spectroscopy measurements. The atomic compositions of the studied crystals are well-matched with composition x increasing from 0 to 1 by intervals of 0.25

Determination of optical constants and temperature dependent band gap energy of GaS0.25Se0.75 single crystals

Optical properties of GaS0.25Se0.75 single crystals were investigated by means of temperature -dependent transmission and room temperature reflection experiments. Derivative spectrophotometry analysis showed that indirect band gap energies of the crystal increase from 2.13 to 2.26 eV as temperature is decreased from 300 to 10 K. Temperature dependence of band gap energy was fitted under the light of theoretical expression. The band gap energy change with temperature and absolute zero value of the band gap energy were found from the analyses. The Wemple-DiDomenico single effective oscillator model and Sellmeier oscillator model were applied to the spectral dependence of room temperature refractive index to find optical parameters of the GaS0.25Se0.75 crystal. Chemical composition of the crystal was determined using the energy dispersive spectral measurements