Ömer Mermer

Effects of PEG loading on electromechanical behavior of cellulose-based electroactive composite

Electroactive behavior of carboxymethylcellulose (CMC)-based actuators was investigated in this study. CMC-based films were firstly fabricated by using 1-butyl-3-methylimidazolium bromide. Characterization studies of the CMC films were conducted by using Fourier transform infrared, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy, and tensile testing. CMC-based actuator films were produced by gold coating on both surfaces of CMC-based films. Polyethylene glycol (PEG) at different loadings (1, 1.5 and 2xa0g) was used to improve electroactive behavior of CMC based actuators. Maximum tip displacements were obtained under DC excitation voltages of 1, 3, 5 and 7xa0V. CMC based actuator loaded with 1.5xa0g PEG exhibited the largest tip displacement among other actuators for each excitation voltage. The PEG loading did not lead to considerable differences in tensile strength of CMC-based films. However, Young’s modulus decreased with PEG loading.

Investigation of the effects of PWM parameters on ionic polymer metal composite actuators

The effects of the PWM excitation signal parameters, such as frequency and magnitude, on the Nafion-based ionic polymer metal composite (IPMC) actuator response were found out. The first set of experiments was designed to observe the actuator response when the actuators were biased with constant DC voltages. These experimental results were exploited to build an experimental data based dynamic model. The model and these results were also used as references to evaluate the experimental results in the proceeding experiments. The second set of experiments was designed to observe the actuator response when the DC square wave signals at different frequencies (0 to 1000 Hz) were applied. The third set of experiments was designed to observe the actuator response when the PWM signals at different magnitudes (6, 8 and 10 V) were applied. It is observed that back relaxation reduces with increasing frequency, but after a certain frequency value, it remains approximately constant. It is seen that the input output relationship of the actuators are linear only for a range of PWM signal magnitudes. The observations in both the PWM frequency and the magnitude experiments indicated that the performance of the Nafion-based IPMC actuator could be improved by selecting a magnitude of PWM signals between 6–8 Volts and by selecting a frequency between 400–1000 Hz.

Assessment of reaction between thorium and polyelectrolyte nano-thin film using Box–Behnken design:

Sandwich type polyelectrolyte nano-thin films (PENTFs) were prepared by using polyallylamine hydrochloride and polyacrylic acid from layer-by-layer assembly process with spin coating system. Their nanostructures have been studied by scanning electron microscope, atomic force microscope, and attenuated total reflectance Fourier transform infrared spectroscopy. In order to understand the effects of the initial concentration of thorium, initial solution pH, temperature, and contact time on the reaction between thorium and PENTF, an experiment data set was designed according to Box–Behnken model. The analysis of variance calculations for regression model were carried out in 95% confidence level and were checked for fitting experimental data and predicted values. The correlation coefficient value (R2) obtained as 94% showed that there was a correlation between the predicted and the observed values. The optimum pH, temperature, initial concentration of thorium, and interaction time in studied ranges were found as 2.81, 35℃, 160u2009mg·L−1, and 120u2009min, respectively. At these conditions thorium (IV) ions adsorption yield was obtained as 89u2009±u20092%. The Freundlich, Langmuir, and Dubinin–Radushkevich isotherms were used to investigate the characteristics of the process. These characteristics data imply that the Freundlich model fits better than the Langmuir model for the Th (IV) sorption onto PENTFs with KF and n values were found to be 20.6u2009mg·g−1 and 1.08u2009L·mg−1, respectively. The thermodynamic parameters were also computed as negative ΔH value suggest that adsorption of Th (IV) is exothermic nature. The calculated negative and positive values of ΔG indicate that the sorption process is favorable (energetically) while running below 40℃ and over this point the process status change to non-spontaneous, respectively.

Effects of SiC particles size on electrochemical properties of electroless Ni-P-SiC nanocomposite coatings

Silicon carbide (SiC) nanoparticles were co-deposited by electroless deposition in nickel-phosphorous (Ni–P) acidic bath. In order to understand the size effect of SiC nanoparticles on the electrochemical properties of the coatings, SiC nano particles with different size (20, 50 and 200 nm) in 2 g/L concentration was added to the bath. All samples was heat treated in 400°C in order to obtain crystalline structure. Potentiodynamic polarization and electrochemical impedance spectroscopy was employed to examine of corrosion performance of the coatings. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) were used for phase and morphological studies, respectively. Experimental results show that SiC particles size in the coating bath affected both composition and morphology of the coating. Presence of SiC nanoparticles in the Ni–P coating with 50 nm increased the corrosion resistance of the coating more than the other sizes.

Evaluation of the Possibility of using Diatomite Natural Mineral as a Composite Agent in Acrylic Coating

In the present study the possibility of the commercially available acryl and diatomite earth (DE) mineral as a composite coating for corrosion protection of Mg alloys has been evaluated. The acrylic coating is used as a top coating in a wide field of applications like automotive, aerospace, medicine and electronics where it shows beneficial properties. Diatomite-dispersed acrylic paint was applied over the substrate by conventional spray technique with an air pressure of 3 kg cm−2. Firstly the acryl was mixed with hardener and then the DE was added to the mixture. Four types of coating with 0, 2, 4, 8 g/L DE have been prepared. The results show that adding up to 4 g/L of the DE improved the corrosion resistance and produced a coating with acceptable surface roughness.

A numerical analysis of thermal management schemes of a LED array in TFT TV

This paper aims to perform the numerical analysis and to investigate thermal characteristics of the LED backlight TFT TV according to thermal design parameters. Natural convective cooling of a LED array system used TFT TV is considered in this study. Numerical computations are carried out for horizontal and vertical orientations of the LED array. The effects of the PCB materials on the temperature distribution are discussed in detail. It is found that the maximum temperature of the LED packages significantly decreases by the horizontal orientation of the LED array in TFT based television. In addition, ceramic based PCB materials having high thermal conductivity such as A1N present better thermal performance than that of metal based PCB materials.