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Article Citation - WoS: 7Citation - Scopus: 7Optical Properties of Gas Crystals: Combined Study of Temperature-Dependent Band Gap Energy and Oscillator Parameters(Natl inst Science Communication-niscair, 2017) Isik, Mehmet; Tugay, Evrin; Gasanly, Nizami; Department of Electrical & Electronics EngineeringOptical parameters of gallium sulfide (GaS) layered single crystals have been found through temperature-dependent transmission and room temperature reflection experiments in the wavelength range of 400-1100 nm. Experimental data demonstrates the coexistence of both optical indirect and direct transitions and the shift of the absorption edges toward lower energies by increasing temperature in the range of 10-300 K. Band gap at zero temperature, average phonon energy and electron phonon coupling parameter for indirect and direct band gap energies have been obtained from the analyses of temperature dependences of band gap energies. At high temperatures kT>> (E-ph), rates of band gap energy change have been found as 0.56 and 0.67 me V/K for E-gi and E-gd, respectively. Furthermore, the dispersion of refractive index has been discussed in terms of the Wemple-DiDomenico single effective oscillator model. The refractive index dispersion parameters, namely oscillator and dispersion energies, oscillator strength and zero-frequency refractive index, have been found to be 4.48 eV, 24.8 eV, 6.99x10(13) m(-2) and 2.56, respectively. The results of the present work will provide an important contribution to the research areas related to the characterization and optoelectronic device fabrication using GaS layered crystals.Article Citation - WoS: 2Citation - Scopus: 5New Magnetic Measurement System for Determining Metal Covered Mines by Detecting Magnetic Anomaly Using a Sensor Network(Natl inst Science Communication-niscair, 2015) Ege, Yavuz; Kakilli, Adnan; Citak, Hakan; Kalender, Osman; Nazlibilek, Sedat; Sensoy, Mehmet Gokhan; Department of Mechatronics EngineeringThe most commonly used remote sensing methods are used in such applications as the aquistic emmission, ground penetration radar (GPR) detection, electromagnetic induction spectroscopy, infrared imaging, thermal neutron activation, nuclear quadruple resonance, X-ray back scattering, neutron back scattering and magnetic anomaly detection. In deciding which type of method has to be used for detection, the variables such as the type of object, material used, position, geographical and environmental conditions, etc. play important roles. In recent years, studies are mainly concentrated on the improvement of detection distance, accuracy, power consumption aspects of remote sensing methods. In the present study, the same concerns are taken into account and a new magnetic measurement system is developed in this context. The system is made up of a sensor network consisting of high sensitive and low power anisotropic magneto-resistive KMZ51 sensors. The sensor network can detect the magnetic anomalies of vertical component of earth's magnetic field created by buried objects as metal covered mines. In the present paper, the effects of physical properties of metal covered materials to magnetic anomalies have been studied. The sensor network is composed of 24 sensors. The voltage levels of each sensor are measured one-by one and transferred to a digital computer where the distribution of the voltages in x-y plane is plotted as 3D graphics. Furthermore, the performance of the system on the detection of buried metallic mines and determination of their shapes have been investigated.Article Citation - WoS: 1Citation - Scopus: 1New Real Time Temperature Monitoring and Evaluation System(Natl inst Science Communication-niscair, 2015) Ege, Yavuz; Kalender, Osman; Citak, Hakan; Nazlibilek, Sedat; Coramik, Mustafa; Department of Mechatronics EngineeringThe storage of many drugs, serum and vaccines at specified temperature limit is very important. Therefore, it is necessary to read and record the ambient temperature and control the refrigerating device according to the limiting values specified by the user. Taking into account these requirements, a new PIC microprocessor-based temperature monitoring system that triggers the DS18B20 temperature sensor and controls the running of the refrigerator system is designed and developed. At the controlling operation, performed by this system, temperature limits are specified by the user. In case these limit values are exceeded, a warning message is sent to the user through GSM module. Furthermore, the temperature values that are read between the time intervals specified by the user are sent to a GLCD screen and presented in a graphical form. The temperature readings can be transferred to the computer environment as text file through a Visual Basic based interface with using a serial port. At this system which has one year data storage capacity, it is possible that the temperature values can be transferred to the computer by wireless communication facility. Differently from the present systems, recording, evaluation, warning and device control operations are performed in the same system. In the present paper, the system operation and its performance at the fields of application are expressed in detail.
