On the equivalent ZIP parameter extraction of desktop computer cases and LCD monitors connected in parallel | Author : Suayb Çagri Yener, Resat Mutlu | Abstract | Full Text | Abstract :Constant-impedance, constant-current and constant-power ZIP models of electrical loads are commonly used in smart grid and residential load applications. Some of residential loads are of nonlinear nature such as LCD monitors and computers. In this study, first, equivalent ZIP model formulas of parallel-connected electrical loads are derived. Then, the ZIP models of an LCD monitor, a computer case and the computer case and the monitor connected in parallel have been obtained using experimental data and least-squares curve fitting method. Finally, the equivalent ZIP model formulas are tested with the experimental data. It has been found that for the rectifier nonlinear loads with different ZIP parameters, the formulas do not give acceptable errors. Therefore, for rectifier nonlinear loads, the measurement-based approach for load modeling must be performed. |
| Investigation on the corrosion resistances of bronze-waste tire-concrete composites | Author : Tuba Bahtli, Nesibe Sevde Ozbay | Abstract | Full Text | Abstract :In this study, finely ground CuAl10Ni bronze sawdust and waste tire additives were incorporated into C30 concrete at different amounts and then their corrosion resistances were investigated. SEM/EDX analyses were performed. It was observed that after acids attacks, as the waiting time in the acid solutions increased, electrical surface resistance values increased due to further corrosion. Also, more losses in the weight were observed in the pure concrete than the concretes including bronze sawdust and waste tire grains, then those refractories showed higher corrosion resistances than that of pure concrete. |
| Using of recycling materials in the construction sector | Author : Ahmet ÜNAL, Ali ÖZ | Abstract | Full Text | Abstract :The fact that the population is increasing day by day requires more careful use of limited resources. Making these limited resources reusable after use has a separate meaning in terms of both the environment and the economy. Therefore; the importance of recycling activities is increasing day by day. The managers of the countries; Due to the increasing importance of recycling activities, they make legal arrangements to encourage these activities. Particularly in the construction sector, because of the extensible resources are used extensively, recycling activities are applied intensively. Within the scope of the study, the recycling activities (asphalt, used vehicle tires, slags, glass waste and marble waste) in the construction sector were researched. In addition, applications after recycling of materials have been examined. The economic contribution of the acquisition of materials through recycling has been expressed. |
| A review study on ladle slag detection technologies in continuous casting process | Author : Hakan KAPUSUZ, Mehmet Ali GÜVENÇ, Selçuk MISTIKOGLU | Abstract | Full Text | Abstract :In steel production, continuous casting method using BOF or EAF is increasing day by day. However, the complex nature of the continuous casting process poses many challenges for steelmakers. During the general steel production process of liquid steel, the state of ladle slag penetration into liquid steel is one of the most influential factors in steel quality. If the ingress of ladle slag into liquid steel cannot be controlled, undesirable results in terms of poor quality, safety and castability can occur. Generally, ladle slag consists of oxides such as CaO, SiO 2, Al 2 O 3, MgO. In conventional methods, the operator prevents the slag entry by manually controlling it. This method is performed directly by the operator, so the error rate is high. For this reason, it is not desired to be used by steel producers who want high quality products. In this context, steel mills carry out various activities to separate slag from liquid steel. The development of sensor technologies has accelerated the slag detection process. Acceleration and magnetic sensors are among the most widely used methods in this field. In this study, the systems used worldwide for the determination of slag in the continuous casting process were investigated and presented. The advantages and disadvantages of these systems are discussed. The detection methods by considering investment cost, detection time, accuracy were compared and presented. In the scope of this study, it is seen that every method has own advantages and disadvantages over other. |
| PAPR reduction performance of bat algorithm in OFDM systems | Author : Yüksel TOKUR BOZKURT, Necmi TASPINAR | Abstract | Full Text | Abstract :The progression in technology requires improved modulation techniques for wideband digital communication systems. Orthogonal frequency division multiplexing is efficacious systems to fulfill high-speed data transmissions needs. However, high peak-to-average power ratio (PAPR) is one of the significant limitations on the performance and power efficiency of OFDM systems. Due to industrial and scientific relevance, the assessment of the PAPR reduction has become popular subject in the current decade. This study presents the combination of bat algorithm with partial transmit sequence scheme as an efficient PAPR reduction method with an alleviated computational load. A set of simulations with different partial transmit sequence schemes are performed to comparatively evaluate the PAPR reduction performance of the partial transmit sequence based on bat algorithm scheme in OFDM system. The simulation results elucidate that BA-PTS scheme can provides better PAPR reduction performance with less computational load. |
| Influence of fabrication temperature on the structural features of chitosan gels for tissue engineering applications | Author : Nimet Bölgen, Seda Ceylan, Didem Demir | Abstract | Full Text | Abstract :Chitosan is a natural polymer synthesized from the chitin of crab, lobster shells, fungal mycelia and shrimp. It has been used for biomedical applications in many different structures including thin film, nanofibrous membrane, sponge, microsphere, hydrogel and cryogel because of its non-toxicity, biodegradability, biocompatibility and antibacterial properties. Cryogelation technique is based on the crosslinking of polymers or crosslinking polymerization of monomers in the presence of crosslinking agents at temperatures below zero. On the other hand, hydrogels are mainly prepared at room temperature. In this study, chitosan gels were prepared at different reaction temperatures (-25, 0 and +25°C). Swelling profiles revealed that with decreasing reaction temperature swelling ratio increased. In addition, the degradation rate of chitosan gels prepared at -25 and +25°C was measured 50.60 and 30.88%, respectively. Results indicate that reaction temperature affects the architecture and characterization results of the gels. |
| Misalignment fault detection by wavelet analysis of vibration signals | Author : Özgür YILMAZ, Murat AKSOY, Zehan KESILMIS | Abstract | Full Text | Abstract :Asynchronous motors are frequently used in many industrial applications, especially pumps and fans. Placement, bearing and coupling faults are common faults in these types of engines. Misalignment error is a common type of error that is seen very often among these errors. This error may cause efficiency decrease in a short run and vibration may cause short circuit and wear in moving parts in the stator windings in a long run. Early diagnosis of such faults is important in terms of machine health and productivity. In this study, loose connection and angular imbalance of the asynchronous machine were investigated. In the experimental works, a 1 Phase 0.75 KW power asynchronous motor, Y-0036-024A Electromagnetic Brake and SKF Microlog vibration meter were used during the measurements. The Frequency components of motor caused by the settlement errors were investigated under the different loads. A loose assembly error and angular imbalance were investigated from the misalignment errors. The engine was run idle and without any positioning errors and measurements were taken from different points with the accelerometer and the frequency spectrum examined. Measurements are repeated when the misalignment errors are occurred on purpose and the FFT frequency components were compared under the load of 12.50Nm using magnetic brake. The results show that the FFT frequency components are examined and the placement error can be determined with high success and accuracy. It has been found that harmonic components are formed in the frequency spectrum at 25Hz Coefficients. After the settlement error is generated it is seen that, undesired frequency components that are unloaded are lowered under load when the frequency spectra is examined. In this study, theoretical and experimental comparisons of settlement errors are made. Although many errors in this subject are examined in the same publication in general, only the results of the settlement errors are examined specifically as a contribution to the literature. The results and graphs are presented comparatively to the readers knowledge. |
| Constrained model predictive control for the quadruple-tank process | Author : Zohra ZIDANE | Abstract | Full Text | Abstract :Model Predictive Control (MPC) is an advanced method of controllers, explicitly uses of model to obtain control signal. MPC is popular in industry and academia because it is capable to deals with non-minimum phase, unstable, dead time and multivariable processes, and solves the problem of constraints. MPC with integral action method is used in this study for the quadruple tank system by taking the lower two tanks into account. The objective of this work is to design and study the MPC method for controlling the level of tanks in a quadruple tank process depending on type of constrained problems. However, to solve the problem of constraints is not easy way. The methods based on the quadratic programming function and ‘if-else’ technique are presented to solve the problem of the process constraints in MPC. A comparative study is performed with the quadratic programming function and ‘if-else’ technique. The performance of the proposed method is tested for reference tracking and disturbance rejection behavior. Simulation results are presented and discussed to show the performance of the controller. |
| An experimental study on production of intelligent textile by using ionocromic materials | Author : Aslihan KORUYUCU | Abstract | Full Text | Abstract :The production of an intelligent textile material that changes color under the influence of pH was researched in this research article. For this purpose, halochromic dyes were used. In halochromic dyes, bleeding and fastness problems are encountered after dyeing. In order to solve these problems; the dye is fixed with cationic fixators in the textile fiber. In this study, a woven nylon fabric was dyed with Alizarin Red S halochromic dyestuff by conventional dyeing method which was followed by post-treated by tannic acid/potassium antimony tartarate at different ratios (1%, 2%, 3%). After dyeing and post-treating, CIELab, K/S, ?E* values were measured by spectrophotometer and compared. In order to investigate the effect of halochromics on the post-treated, dyed and post-treated fabrics were immersed in 5 different solutions prepared by using HCl and NaOH between pH 2 and 10, and the samples were removed after 1 hour and the color change in the samples was compared. After the process, the speed of fixation of the dye molecule onto the fiber was increased. |
| TEM characterization and synthesis of nanoparticle B4C by high-energy milling | Author : Hakan Gökmese, Bulent Bostan, Talha Alper Yilmaz, Ufuk Tasci | Abstract | Full Text | Abstract :In this study, nanoparticle B4C synthesis was carried out by high-energy milling. For this purpose, B2O3-C-Mg triple systems were used in the reaction stoichiometric ratios as starting materials in the experimental studies. The reduction process of B2O3 was performed using speks type milling device. The transformation of the ceramic phase of the nanoparticle B4C by XRD analysis was examined. In terms of microstructural characterization of its powder shape and morphology, TEM (imaging and selected area diffraction pattern) investigations were conducted. The product synthesized by the leaching process was cleaned from MgO/B4C impurities and the production of the nanoparticle B4C was performed. After leaching processes, it was determined that some of the synthesized powders were below 50 nm, while others varied between the ranges of 50-350 nm. In TEM examinations of B4C particles carried out after leaching process, it was seen that there were twin formations observed as planar error. Depending on the d values calculated by solving the TEM diffraction patterns, the planes represented by nano-sized B4C particles were determined. |
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