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Acoustic and Thermal Properties of Polypropylene Carpets: Effect of Pile Length and Loop Density
Merve Küçük,Yasemin Korkmaz 한국섬유공학회 2019 Fibers and polymers Vol.20 No.7
Sound control in office and living environments is cruical for creating a peaceful and relaxing occupation forindividuals. Improvement of sound absorption properties of textile materials used in architectural structures has become anissue of importance. The study here is focused on acoustic characterization of polypropylene carpets used in the indoorenvironments. Due to growing interest in mass, volume and cost efficient multifunctional materials, additionally thermalconductivity of the carpets have been studied. Polypropylene carpet samples were prepared with four different pile length andtwo different loop density parameters. It has been observed that loop density and pile length parameters affect thermalproperties and sound absorption rates all frequency ranges. Anova analysis for sound absorption revealed that the combinedeffect of loop density and pile length parameters is evident in the mid-to-high frequency ranges.
Application of Taguchi method in the optimization of dissolution of ulexite in NH4Cl solutions
Özkan Küçük 한국화학공학회 2006 Korean Journal of Chemical Engineering Vol.23 No.1
Taguchi method was used to determine optimum conditions for the dissolution of ulexite in NH4Clsolutions. The ranges of experimental parameters were betwen 50-87oC for reaction temperature, 0.05-0.20 g·mL14Cl concentration, 5-25 min for reaction time, and (850+600)-(90) m forparticle size. The optimum conditions for these parameters were found to be 87oC, 0.05 g·mL1, 4 M, (30+212)m, and 18 minutes, respectively. Under these conditions, the dissolution percentage of ulexite in NH4Cl solution was98.37. Reaction products were found to be boric acid, ammonium tetraborates, sodium tetraborate decahydrate, calciumchloride, and sodium chloride.
The meaning of the concept of lacunary statistical convergence in G-metric spaces
Şerife Selcan Küçük,Hafize Gümüş 강원경기수학회 2022 한국수학논문집 Vol.30 No.4
In this study, the concept of lacunary statistical convergence is studied in G-metric spaces. The G-metric function is based on the concept of distance between three points. Considering this new concept of distance, we examined the relationships between $GS,$ $GS_{\theta },G\sigma _{1}$ and $GN_{\theta} $ sequence spaces.
Design, Fabrication and Vision Based Operational Analysis of Novel Shape Memory Alloy Micro Grippers
Özgür Yurtsever,Haluk Küçük 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.9
Object grip, grasp, hold and place type of tasks incorporate specific engineering design concepts. Considering such principals, eight gripper mechanisms were designed and produced which can be classified as micro grippers due to their small workspace, precise grasping and holding abilities. Common characteristics of all the designs are that, without using any electric motor, the open–close operation is by virtue of shape-memory alloys. Each gripper is designed for different purposes with different operational principles of which four were initially open and the other four were initially closed configurations. Parametric studies were performed by changing the duty cycle and frequency of pulse width modulation using a signal generator followed by measurement of gripper jaw clearance, open–close period, average open–close velocities, gripping force, holding and lifting abilities of the designed gripper mechanisms. Jaw displacement and velocity parameters were computed by image processing of video records captured during the operation of the gripper mechanisms.
Fault Diagnosis of Bevel Gears Using Neural Pattern Recognition and MLP Neural Network Algorithms
Cemal Keleşoğlu,Haluk Küçük,Mustafa Demetgül 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.5
Gear mechanisms are key components for rotating machinery ranging from automotive, hydraulic systems to aviation systems. As a more reliable, safer, economical fault diagnostic method, vibration and acoustic signatures of such systems havebeen widely studied. There are only a few numbers of studies incorporating sound and vibration monitoring together, fordiff erent working hours of the mechanism, rotating at diff erent operational parameters. A bevel gear test setup was developedin-house to observe the eff ect of diff erent operating conditions as shaft loading, shaft speed, lubrication level and abrasivecontamination along with diff erent operating hours. The system operating condition was also monitored, by obtaining visualphotographs of gear teeth. Vibration and sound signals were recorded followed by fast Fourier Transform and Power SpectrumDensity computations to extract the features used in developing a Multi-Layer Perceptron (MLP) based Neural Networkand a Neural Pattern Recognition algorithm for fault classifi cation purposes. It has been shown that sound and vibrationmeasurements can be confi dently used to predict bevel gear fault conditions.
Ferhat Bülbül,Hikmet Altun,Özkan Küçük,Vefa Ezirmik 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.4
This study aims to evaluate the tribological and corrosion properties of the electroless Ni-B coating deposited on AISI 304 stainless steels. The microstructure of the coating was characterized using x-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). XRD analysis revealed that the prepared coating possessed an amorphous character. SEM-EDS investigation also indicated that a non-stoichiometric Ni-B coating was deposited with a columnar growth mechanism on the stainless steel substrate and the morphology of the growth surface was blackberry-like. The hardness and tribological properties were characterized by microhardness and a pin-on-disc wear test. The electroless Ni-B coated sample had a higher degree of hardness, a lower friction coefficient and a lower wear rate than the uncoated substrate. The electrochemical potentiodynamic polarization method was used to evaluate the corrosion resistance of the coating. The electroless Ni-B coating offered cathodic protection on the substrate by acting as a sacrificial anode although it was electrochemically more reactive than the stainless steel substrate.