The flyback micro-inverters operating at discontinuous conduction mode are very attractive due to the operation in open loop and working without current sensor. In this paper, the working characteristics of a grid-connected photovoltaic micro-inverter based on flyback converter are investigated and design details are presented. “Perturbation and observation” method is used for maximum power point tracking. A micro-inverter prototype of 80 Wp is designed and produced. All the inverter functions, such as maximum power point tracking, islanding protection, serial communication, power control etc., are implemented by PIC24FJ64GA002 microcontroller. The measurements taken from protyped micro-inverter are compatible with design values. The highest efficiency of the converter was found as 80% and the loss mechanisms are discussed.

In this study the principles of a frequency shift keying optical MODEM design have been investigated. In this MODEM modulated digital data has been transmitted between transmitter and receiver via light in the free space. An infrared LED light has been modulated by FSK modulated signal at the transmitter and this modulated light has been converted to an electrical signal using a photo detector at the receiver end. The communication distance depends on both LED’s radiant power and photo detector sensitivity. In many available applications the photo detector sensitivity and receiver gain have been increased to increase communication distance. In this study LED’s radiant power has been increased rather than photo detector sensitivity. Beside of increasing communication distance the background noise effect has been decreased by driving LEDs with pulsed high currents.

The shielding efficiency of cylindrical shields for three phase underground cable is investigated for several shields material using finite element method (FEM). This FEM model takes into account the nonlinear hysteretic behavior for ferromagnetic material in the shield. The shields are cylindrical shaped and the power cables are positioned in flat configuration. The shielding efficiency is compared for shields with the same geometry but several shielding materials with nonlinear hysteretic behavior (Magnetil and DX52, both from Arcelor-Mittal firm) and a non-ferromagnetic and electrically conducting shielding material (Aluminium). The paper investigates the influence of several parameters on shielding efficiency: the size of the shield radius, the current amplitude in the cable and the thickness of the shield. Magnetil shield material is the best in terms of shielding performance.
The numerical models are validated with experimental results for without shield.

In this study, a square-root-domain (SRD) electronically-tunable second-order trans-admittance type filter is proposed. The proposed filter has one voltage input and two current outputs and can simultaneously realize low-pass (LP) and band-pass (BP) responses without any changes in the circuit topology. Additionally, trans-admittance type second-order universal filter that has low-pass, band-pass, high-pass (HP), all-pass (AP) and notch (N) outputs is realized by adding a circuitry. The transfer admittance parameter g0, natural frequency f0 and quality factor Q of the trans-admittance type filter can be electronically tuned by changing DC control current sources. Some time and frequency domain simulations are performed using PSPICE program for the proposed trans-admittance type filters.

In this study, the test results were compared with the parameters specified and determination of parameters of the design Double-Side Linear Permanent Magnet Synchronous Motor. Firstly given the design details of the motor and then transferred to the methods used to obtain the parameters of the motor. Three different methods were used in finding the parameters. The first of these methods, the classical method, the experimental method. The second is a digital LCR meter sensitive results obtained. The third one the motor drive
LG-SV022ÝG5A-4 results obtained from the product code. With these results, the motor was tested with the help of computer software is prepared. From the results of the test current, frequency, and the results were evaluated given pushing force and speed graphics.

In this paper a fuzzy controller is applied to velocity and direction angle control of a certain type of wheeled mobile robots called Automated Guided Vehicles (AGVs). The velocity and direction angle of the AGV are controlled to keep the vehicle on desired path. A PI controller is also applied to AGV in order to show the robustness of the fuzzy controller. Experimental results prove that the fuzzy controller shows better tracking performance than the PI controller in terms of robustness, smoothness and fast dynamics. Results are also given for sudden disturbance and extra load conditions and satisfied results are obtained.

A temperature sensor is proposed in the computational environment using triangular lattice GaAs photonic crystal structure and the sensitivity of the sensor is enhanced by employing structural improvements around the cavity and by using slow light feature. By creating a point defect one row ahead from the photonic crystal waveguide, light in the cavity resonance frequencies is coupled to this point defect and the change of the resonance frequency related to the temperature is investigated. The radius of the holes around the cavity and the cavity area are changed to enhance the sensitivity. 0.1001 nm/ºC sensitivity of the temperature sensor is increased by 1.4%±0.1% with structural optimizations. Light is slowed down by 14 times in a 20.23 nm range including the cavity resonance wavelength by changing the radius of the first rows of holes surrounding the waveguide and shifting them in a direction parallel to the waveguide. The sensitivity of the sensor is increased by 2.8%±0.1% as a result of increasing optical overlap of the mode with the cavity by slow light effect.