In this work, we use first-principles calculations based on density-functional theory generalized gradient approximation (Perdew Burke Ernzerhof, PBE). Cubic and hexagonal AgBiS2 structures have been performed using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method to investigate the structural, optical and electronic properties. We have calculated the ground-state energy, the lattice constant, DOS, band gap and dielectric constant of cubic and hexagonal AgBiS2 by using Wien2k packet. The calculated physical properties of silver bismuth sulfide are compared with the experimental results and good agreement was observed.

The aim of this study was to determine the effects of nTiO2Ag, co-application of nZnO and nTiO2Ag and co-application of EDDS as an organic acid with nTiO2Ag on seed germination, seedling vigor, plumule and radicle length of rye. Ten seeds were placed in petri-dishes with double layer of filter paper which used as an inert material. Then 5 mL nTiO2Ag, nZnO-nTiO2Ag and EDDS-nTiO2Ag suspensions were added to every petri dish with different concentrations (control, 50, 100 and 200 mg/L). Treatment of nZnO-nTiO2Ag, especially at concentration of 50 mg/L, promoted the germination rate, seedling vigor, plumule and radicle elongation. The highest seedling vigor index (SVI) was observed at concentration of 50 mg/L nZnO-nTiO2Ag. Seedling vigor index of rye seeds was decreased after treatment of nTiO2Ag. The plumule elongation increased with treatment of all test chemicals and radicle elongation was increased nZnO-nTiO2Ag and EDDS-nTiO2Ag exposure compared to control. This is the first report on the effect of co-application of ZnO-TiO2Ag nanoparticles and co-application of EDDS-TiO2Ag nanoparticles on rye growth.

Present study is focused on numerical investigation of heat transfer and fluid flow from a heated surface by using nanofluids and impinging jets. Effects of Reynolds number, different particle diameter and different types of nanofluids (TiO2-water, CuO-water, NiO-water) on heat transfer and fluid flow were studied numerically. TiO2-water nanofluid was used as a base coolant. Three impinging jets were used to cool the surface. It is obtained that increasing jet velocities from Ren/Re1=1-1.33-1.67 to Ren/Re1=1-1.20-1.40 causes an increase of 49.9% on average Nusselt number (ANN) but increasing jet velocities from Ren/Re1=1-1.20-1.40 to Ren/Re1=1-1.17-1.33 causes a decrease of 4.6% on ANN. Particle diameter from Dp=80nm to 10nm causes an increase of 2.9% on ANN. Using NiO-Water nanofluid causes an increase of 1% on ANN with respect to CuO and 2.8% with respect to TiO2-water. Low Re k-e turbulent model of PHOENICS CFD code was used for numerical analysis. Numerical results show a good approximation to experimental results.

In this research paper, pre-alloyed NiTi based shape memory alloy and 4%Cu were used as starting powder materials. Starting powder materials were blended for 60 minutes by a turbula mixer. After mix processing, microstructure and phase transformations of powders were characterized using X-ray (XRD), elemental distribution spectrometry (EDS), scanning electron microscopy (SEM). Prepared powder mixtures as NiTi and NiTi+4%Cu alloys were pressed at 785MPa in a mold and then sintering process was applied to materials at different temperatures and time. Formation of multiphase’s (Ni3Ti, NiTi, Ti2Ni, Ni4Ti3 and NiTiCu) and positive effects of Cu addition were obtained by sintering at different temperatures and time. And also, stabilized NiTi phase and increasing the value of micro hardness were determined with added 4%Cu powders.

This paper presents a novel scheme for solving inverse kinematics problem (IKP) of a multi-link robotic manipulator. Important features of the proposed strategy are generality and simplicity regardless of the number of degrees of freedom (DOF) and geometry of the robot. The proposed method is a feedback strategy where the IKP solution is expressed as a dynamic control system whose goal is to maintain satisfactory trajectory tracking. As a simulation test to reveal the performance of proposed scheme, a four DOF Selective Compliance Assembly Robot Arm (SCARA) system is considered. Feedback law in proposed closed-loop solution method is selected as a combination of Sliding Mode Control (SMC) and Proportional-Derivative (PD) control for providing simplicity and robustness. Simulation results are used to show the efficacy of proposed IKP solution approach in comparison with commonly used neural networks (NN) based IKP solution method. Results reveal that proposed method yields the solution of IKP with satisfactory performance.

This paper describes an autopilot system design to regulate the altitude, heading and forward speed in the fixed-wing flight mode of the Osprey V22 VTOL (vertical takeoff and land) tilt rotor UAV accordingly to a reference, which is generated the trajectory sub-block. X- Plane flight simulator developed by Laminar Research, is used to test and optimize the parameter values of the autopilot system, which is designed using feedback, feedforward and PID controllers in MATLAB / Simulink environment (Software in the Loop- SIL). The receiver and sender blocks to perform the data interactions between MATLAB / Simulink and X-Plane flight simulator are created in MATLAB / Simulink environment. The receiver block is used to transfer data from the X-Plane flight simulator to the controller, while the sender block is used to transfer control signals from the controller to the X-Plane flight simulator program. The data communication between the two is UDP. The autopilot system under test is embedded in the Raspberry-Pi minicomputer and a hardware-in loop (HIL) test system created. The reaction of the control algorithm running on the Raspberry-Pi minicomputer to the virtual sensor data generated by the X-Plane flight simulator investigated. It is observed that, the Osprey-V22 aircraft can perform tasks autonomously in the horizontal flight mode, from the experiments and the results obtained. This study also describes the first stage of an undergoing project which aims to develop a robust autopilot for Osprey V22 VTOL UAV.

In this study, some pretreatments were applied to cow manure to determine water solubility and biogas production. Aqueous phases containing 10 % solids by mass were prepared in the study. Chemical substances (NaOH), which were as much as 10, 15, and 20 % of the solids by mass, were added to the aqueous phases, and then they were subjected to microwave and hotplate thermal pretreatments separately (for 15, 30, 60 minutes). Following the pretreatments, the water solubility percentages of the solid materials were determined in the un-pretreated and pretreated aqueous phases. The pH of the aqueous phases, which yielded the highest water solubility, was adjusted to 7 using acid. Afterwards, the aqueous phases were incubated at 35 °C for 32 days in an incubator, and biogas and methane measurements were made in aqueous phases every 4 days. As a result of the study, maximum water solubility was found to be 92.8% (by mass), maximum biogas yield 378 mL/1g, and dry solids and maximum methane content values 41%.

Depending on the growing population and the developing industry, wastewater is encountered with different characteristics and higher temperatures each passing day. For this reason, researches are under way for new treatment methods that will respond to needs in terms of cost and remediation. In this study, treatment of fruit juice concentrate wastewater has been examined by electrocoagulation (EC). For this purpose, the optimum conditions for the best COD removal were investigated. In the EC process, different electrodes (aluminum, iron and steel), pH (5.5,7, 8 and 9) and current (0.6, 0.8 and 1.0 A) were studied, respectively. The results showed that the optimum COD and color removal were obtained as 66%, 98% respectively when the applied electrode pair were Al(+)/Fe(-), cell current was 0,8A and wastewater pH was 5.5 in 10 min. Also, the operating cost was calculated for the optimized treatment conditions of 1 m3 fruit juice wastewater as 2.69 US$.

The major challenge for the production of the composites which are reinforced with nano and micro-sized particles is to obtain uniform distribution of reinforcement particles in microstructure. Powder metallurgy method can be used in order to obtain a homogeneous distribution of reinforcement particles. This method has three steps: 1) mixing and/or alloying of powders, 2) pressing, and 3) sintering. Mechanical alloying is a complex process which involves optimization of many parameters such as milling time, process control agent, particle size, ball to powder weight ratio, milling speed, milling atmosphere, mill types, etc. The main aim of the present study is to explain the roles of volume fraction and size of reinforcement particle on the microstructural properties and how these parameters affect the mechanical properties of aluminum based metal matrix composites with micro and nano-sized reinforcement particles produced by mechanical alloying.

Throughout history, mankind has made progress in social and technical areas by finding many energy sources and developing energy systems. For this reason, energy is a necessary and indispensable issue. Today, due to the increasing demands, the energy requirement has increased even more than in the past. In order to increase this energy capacity, researches and studies have been carried out on the use of energy systems more efficiently. They will be also carried out in the future. In the new global world, great progress has been made in the energy systems technology and very different systems have been found. It is clear that these systems provide high benefits in many sectors, especially in the industrial and transportation sectors. In order to use the energy for their internal consumption, and also export it, the developed countries have power plants with large production capacity. For this reason, the developed countries are competing with each other in energy issues. Producing mechanical and electrical energy, using underground energy sources and alternative energy sources are the major factor which keeping pace with the changing world. In this study, it has been tried to give technical and statistical information about the use of natural energy, natural gas, coal and nuclear energy sources and renewable energy systems such as wind, solar, hydro and biomass. We emphasized which energy system the world head toward for certain years. In addition, the advantages and disadvantages of these systems have been demonstrated.

Nitrogen fertilization in vegetable production in agriculture is an inevitable application for plant growth and yield. The use of urea (46%)and nitrate (23-26%) for nitrogen fertilization is common in our country s agriculture. Nitrogen fertilization is carried out two or three times in different periods to meet the nitrogen requirement of the soil in wheat farming. Nitrogen fertilization is performed once in the pre-sowing period in developed countries such as America and Canada. Studies have also been carried out in order to ensure the use of similar nitrogen fertilization methods under the conditions of our country. Anhydrous ammonia, which is a raw material of nitrogenous fertilizers with 82.2% nitrogen content, was used for fertilizing as an environmental and economic method. The biggest problem in this application is the lack of equipment that can place the fertilizer into the soil due to the chemical properties of Anhydrous ammonia. In our work, we have developed equipment for the application of anhydrous ammonia and have carried out experiments on wheat farming in the region. Two different methods have been studied in the research; Anhydrous ammonia methods and traditional methods. The anhydrous ammonia method is a more advantageous method than the farmer condition method in terms of the parameters examined. Anhydrous ammonia method is a more environmentally and economical method due to the use of less fertilizer.

Chaos is one of the important research areas in recent years. The chaotic signal generator is one of the most basic structure in the chaos-based researches and applications. In this study, Sundarapandian-Pehlivan Chaotic Oscillator (SPCO) designs have been implemented in 2 different platforms as analog-based using Second-Generation Current Controlled Current Conveyor (CCII) and FPGA-based with one of the chaotic oscillator that has been presented to the literature namely Sundarapandian-Pehlivan system. The structure used for the design of CCII-based chaotic oscillator and the results obtained from the study have been presented. In the second phase, the design of SPCO has been realized in order to utilize for running in FPGA chips using Dormand-Prince (DP) numeric algorithm. The design has been coded in VHDL using 32-bit IEEE-754-1985 floating point representation. The designed system has been tested by synthesizing it in Xilinx ISE Design Tools program. Then, the test results obtained from DP-based SPCO structure have been presented. In the last phase, the designed system has been synthesized for VIRTEX-7 FPGA. FPGA chip resource consumption values that obtained after the Place-Route process are presented. According to the results, the maximum operating frequency of DP-based SPCO unit on FPGA is obtained as 362.608 MHz. In future studies, the designs of Pseudo Random Number Generator (RNG) and True RNG can be performed using DP-based SPCO unit implemented successfully in this study.

In this study, biocompatible polyvinylpyrrolidone (PVP) based nanofiber production was carried out with various polymer and surfactant concentrations. Firstly; various concentrations of PVP (6, 8, 10, 12, 14, 16 wt %) polymer solutions were prepared, solution properties (conductivity, viscosity, surface tension, pH and density) were determined and nanofiber production was achieved under the optimum process parameters. 12 wt % PVP concentration was chosen as an optimum in terms of nanofiber morphology and fiber fineness. Then, polymer concentration was kept constant at 12 wt % and various concentrations of surfactant (1, 2, 3, 4, 5, 6 wt %) added into the polymer solutions. According to the solution properties and Scanning Electron Microscope (SEM) images; conductivity, viscosity and average fiber diameter increased with polymer and surfactant concentrations increasement and ultra-fine, bead free and uniform nanofibers were obtained. On the other hand, surface tension and pH values were affected by polymer concentration changing, however, surface tension decreased significantly and pH decreased slightly with the addition of surfactant to the PVP polymer solution. Moreover, the density of polymer solutions increased with both polymer solution and surfactant concentration increasement.

In recent years, intercity transportation has gained momentum towards high-speed rail in Turkey. Ankara-Konya, Ankara-Eskisehir and Istanbul lines were opened for high-speed transportation in this area. There are still high-speed train lines under construction. At the same time, there are also various high-speed rail projects that will be started soon and are in the designing process. However, these projects require a big budget. Because of this, it is not possible to carry out all the projects and some projects are carried out gradually. In this study, prioritization of the high-speed rail projects was done by using the analytical hierarchy process (AHP). As a result of prioritization made through criteria determined by literature review and expert opinion, evaluations are made.

Energy is a basic necessity after the industrial revolution in our lives. Energy demand is increasing with the development of technology from day by day. Humanity has head towards to the alternative energy sources. Therefore, alternative energy must have renewable sources. This situation can be supply a significant benefit for future energy demand. These resources play an important role in meeting the demand and provide significant benefits in terms of economic and environmental protection. Among the renewable energy sources have taken an important place like hydroelectric power plants, wind turbines, geothermal energy, wave energy, biomass energy, rock gas, etc. However, solar energy is the biggest renewable energy potential most countries in the world. Various countries around the world use renewable energies solar energy and photovoltaic panel technology to choose energy production and increasing the production potentials day by day. In this study, samples will be compared to the United States and Turkey in energy production from solar energy.

In this work, we use first-principles calculations based on density-functional theory generalized gradient approximation (Perdew Burke Ernzerhof, PBE). Cubic and hexagonal AgBiS2 structures have been performed using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method to investigate the structural, optical and electronic properties. We have calculated the ground-state energy, the lattice constant, DOS, band gap and dielectric constant of cubic and hexagonal AgBiS2 by using Wien2k packet. The calculated physical properties of silver bismuth sulfide are compared with the experimental results and good agreement was observed.

The electric field optimization minimizing the field strength on an electrode surface and providing its uniformity is important in designing high voltage power transformer bushings and other apparatus from the viewpoint of efficient utilization of the electric field space. The high voltage power transformer bushing with cylinder electrode system has been designed and tested in this investigation. It was found that the insulation method of the cylinder electrode was the most important factor to lower streamer initiation voltage. The optimized design uses both internal and external elements for electric stress grading at critical parts of the bushing. Applying optimization theory based on charge simulation method, the author developed a computation program for electric field automatic optimization in 3D dielectric axisymmetric field. The results of the computation realized some excellent electrode profiles with uniform electric field distribution. Moreover, the discrepancy from the electric field uniformity on 3D dimensional profile caused by applying it to an axisymmetric electrode was discussed. Then a new electrode with uniform field distribution was obtained by using the computation program for optimization.